Author Topic: Hall Sensors  (Read 11348 times)

Offline Mosey

  • Full Member
  • ****
  • Posts: 1583
  • Rosemont, New Jersey, USA
Hall Sensors
« on: January 17, 2014, 11:21:44 PM »
I have a new ignition system based on Jerry Howell's TIM-6 model, and it failed quickly after initial testing. I suspect the Hall Sensor or the Transister is at fault. I have tested the Transister, and would like to now test the Hall. Does anyone know a simple multimeter test for these components to check it?
Mosey :headscratch:

Offline stevehuckss396

  • Full Member
  • ****
  • Posts: 1367
  • Sterling Heights, MI
    • Steve's Miniature Sparkplugs
Re: Hall Sensors
« Reply #1 on: January 17, 2014, 11:30:43 PM »
I have a new ignition system based on Jerry Howell's TIM-6 model, and it failed quickly after initial testing. I suspect the Hall Sensor or the Transister is at fault. I have tested the Transister, and would like to now test the Hall. Does anyone know a simple multimeter test for these components to check it?
Mosey :headscratch:


As the magnet gets waved over the sensor the output lead should go between 0 and system voltage.
Do not be like the cat who wanted a fish but was afraid to get his paws wet.

Offline Don1966

  • Full Member
  • *****
  • Posts: 5940
  • Morgan City, LA (Along the Gulf Coast)
Re: Hall Sensors
« Reply #2 on: January 17, 2014, 11:59:00 PM »
Mosey, disconnect the positive lead from the Hall device and momentary short out the other two leads. This should trigger the TM6 board. The board can be used for Hall Device or points. Just simulate the points to test the board. Then if the board works you know your Hall device is bad.
You can also test the Hall sensor by putting one lead of the meter to controlled lead of the Hall Sensor and one to the negative lead. Connect one side of a 10k or simulator resistor to the positive power lead and the other lead to the Hall Sensor positive lead. Make sure the negative lead in connected to the Hall Sensor, Pass the magnet in front of it and the voltage should turn on and off.

Don
« Last Edit: January 18, 2014, 12:07:35 AM by Don1966 »

Offline Mosey

  • Full Member
  • ****
  • Posts: 1583
  • Rosemont, New Jersey, USA
Re: Hall Sensors
« Reply #3 on: January 18, 2014, 12:04:39 AM »
Thank you, gentlemen, the check is in the mail.
Mosey
 :praise2:

Offline gbritnell

  • Full Member
  • ****
  • Posts: 1925
Re: Hall Sensors
« Reply #4 on: January 18, 2014, 02:50:55 AM »
Hi Mosey,
I can't add any more to what's been explained but I do have some other bits of information that might be helpful.
When I got started with electronic ignitions one of the first ones I used was made by a fellow on the west coast, a TIM-3. I apologize as I have forgotten his name. The next one I purchased was a TIM-6 from Jerry Howell. Being somewhat handy with a soldering iron I bought the kit and assembled it myself. With it I bought the twin fire coil which is no longer available. I have been using this setup for years with no problems. Through the years Jerry (when he was alive) updated this ignition and over that time I bought several more but with the coils that were then available. That's when I started having a problem. The problem was the ignition would burn out and being that the ignition was the same over the years I suspected the new coils. I contacted Allan Howell, Jerry's son and told him of my findings and the situation. He had just taken over the business and said he wasn't really knowledgeable about the ignitions but if I was having trouble with the coil he would replace it, which he did. Try exchanging or returning electrical components! With the new coil I hooked up my ignitions, one by one and found that they were still heating more than my old original one. At this point I didn't know what to do, and still don't. I have 2 Jerry Howell ignitions that work flawlessly and 2 S&S ignitions that also work fine but I also have 3 other Howell's that will only work with my original coil.
I did have Hall problems early on but since I am religious about making sure I have a good ground before firing up my engines I haven't had any burnouts in years.
Where am I going with all this information, once you know you have a good Hall use your ignition but check the components on the board for overheating. Either the large diode gets hot or the switching transistor. The ignition will work when first started up but then the spark gets weaker and weaker as it gets hot and then quits making sparks.
gbritnell
Talent unshared is talent wasted.

Offline Admiral_dk

  • Full Member
  • ****
  • Posts: 1275
  • Søften - Denmark
Re: Hall Sensors
« Reply #5 on: January 18, 2014, 12:09:00 PM »
Ignition coils should be matched for current, voltage and rpm. What do I mean with that statement ?

All coils have a reluctance to change the current through them, this is the inductance, measured in Henry's and a saturation current / magnetic saturation. In a perfect world (almost all never ECU's in cars and motorcycles) you want to stop the current exactly when it reaches the saturation point and therefore the ECU calculates the exact point in time where it starts the current. This is fine, but your simple circuits can't do that, so the best way to solve the problem, is to do what was used in racing engines before the modern ECU => add a power resistor in series with the primary on the ignition coil. Value between 0.5 and 3 Ohms should do the trick - minimum 5 Watts (10-50W model in metal house would be perfect), if not, you have a mitch matched coil. This resistor also protects the power transistor / MosFet that's used instead of points (the resistor works with points too).

So in Georges case - leave those combinations that works without being too hot alone and experiment with a resistor in those combinations that gets too hot.
« Last Edit: January 18, 2014, 12:13:29 PM by Admiral_dk »

Offline cfellows

  • Full Member
  • ****
  • Posts: 1700
Re: Hall Sensors
« Reply #6 on: January 18, 2014, 07:31:04 PM »
Since I am about to go down this path as well, using the S/S engineering ignition systems, coil included, I have a couple of questions.

First of all, how do you determine which of the poles on the magnet is the south pole?  I've read that the earth's north pole is actually a south magnetic pole which is why it attracts the north pole of a compass.  So, does that mean that I would use the magnet's pole which is attracted to the north pole of a compass?

Also, what are the precautions I need to take to not burn out the hall effect sensor when I first test it and/or install it?

Chuck
So many projects, so little time...

Offline Jasonb

  • Full Member
  • *****
  • Posts: 6361
  • Surrey, UK
Re: Hall Sensors
« Reply #7 on: January 18, 2014, 07:52:51 PM »
The other option is to have different coils wound. I have just taken delivery of some prototype low tension coils from Minimag for evaluation, all have different windings which will affect current and Henrys. Will report how they perform in a few weeks. Julian could also wind you HT coils to your spec.

Offline Don1966

  • Full Member
  • *****
  • Posts: 5940
  • Morgan City, LA (Along the Gulf Coast)
Re: Hall Sensors
« Reply #8 on: January 18, 2014, 08:00:44 PM »
Since I am about to go down this path as well, using the S/S engineering ignition systems, coil included, I have a couple of questions.

First of all, how do you determine which of the poles on the magnet is the south pole?  I've read that the earth's north pole is actually a south magnetic pole which is why it attracts the north pole of a compass.  So, does that mean that I would use the magnet's pole which is attracted to the north pole of a compass?

Also, what are the precautions I need to take to not burn out the hall effect sensor when I first test it and/or install it?

Chuck

Chuck just pass the magnetic across the face of the hall device to see if it triggers. If it doesn't try the opposite side. Try to limit your current to no more than 20MA, you shouldn't need more then that to trigger a circuit.

Don

Jason did you get Julian's  Start up box? It is quiet simple to put together and great to test your Hall sensors with.

Offline Jasonb

  • Full Member
  • *****
  • Posts: 6361
  • Surrey, UK
Re: Hall Sensors
« Reply #9 on: January 18, 2014, 08:05:18 PM »
Not this time as those coils are for an engine with an ignitor so no Hall sensor or points needed.

J

Offline derekwarner

  • Full Member
  • ****
  • Posts: 474
  • Wollongong ...... Australia
Re: Hall Sensors
« Reply #10 on: January 18, 2014, 08:18:15 PM »
Chuck....another option is to use a pre-stamped pole piece...very inexpensive...we use them as installation aids/tools which attracted the opposite pole in small rare earth magnets when the latter were being installed into transducer magnet rings....

Initially we found these rings very difficult to manufacture as each of the 4 diameter x 4 long REM's after being inserted in the magnet ring holes would naturally jump out of the hole & attract upside down to an opposite mate

A number of transducer rings failed on test........it was then we discovered a number of REM pole pieces had flipped  :lolb:

So the pre stamped pole piece was also used as a final checking device for polarity...... :happyreader:...Derek



Derek
« Last Edit: January 18, 2014, 08:25:00 PM by derekwarner_decoy »
Derek Warner - Honorary Secretary [Retired]
Illawarra Live Steamers Co-op - Australia
www.ils.org.au

Offline Rustkolector

  • Full Member
  • ****
  • Posts: 79
Re: Hall Sensors
« Reply #11 on: January 18, 2014, 09:46:01 PM »
Chuck,
Easy way to determine south pole of magnet is to put it near a compass. The compass north will point to the south pole of the  magnet.

Jeff

Offline tvoght

  • Full Member
  • ****
  • Posts: 919
  • Indiana
Re: Hall Sensors
« Reply #12 on: January 18, 2014, 10:16:48 PM »
I was able to mark a small bar magnet by placing it on a piece of waxed paper and gently laying it down to float on the surface of a bowl of water. The north pole sought north and the magnet was marked accordingly.

--Tim

Offline stevehuckss396

  • Full Member
  • ****
  • Posts: 1367
  • Sterling Heights, MI
    • Steve's Miniature Sparkplugs
Re: Hall Sensors
« Reply #13 on: January 18, 2014, 10:27:14 PM »
Since I am about to go down this path as well, using the S/S engineering ignition systems, coil included, I have a couple of questions.

First of all, how do you determine which of the poles on the magnet is the south pole?

Also, what are the precautions I need to take to not burn out the hall effect sensor when I first test it and/or install it?


First question. wire up the ignition to a sparkplug on the bench and then wave the magnet over the sensor to find out what side fires the plug. Done.

Best money spent is to put a heavy ground wire (#14) right from the low voltage side of the coil to the engine block. Bolt the wire to the block with a nice clean connection and the proper terminal. I glue the sensor right down to a metal surface and get years out of them.
Do not be like the cat who wanted a fish but was afraid to get his paws wet.

Offline Mosey

  • Full Member
  • ****
  • Posts: 1583
  • Rosemont, New Jersey, USA
Re: Hall Sensors
« Reply #14 on: January 18, 2014, 10:43:55 PM »
I plan to buy a cheap magnetic Scotty dog in the toy store to find the North of my magnets, as I tend to lose track.
Mosey
« Last Edit: January 18, 2014, 10:51:08 PM by Mosey »

Offline stevehuckss396

  • Full Member
  • ****
  • Posts: 1367
  • Sterling Heights, MI
    • Steve's Miniature Sparkplugs
Re: Hall Sensors
« Reply #15 on: January 18, 2014, 10:54:54 PM »
I plan to buy a cheap magnetic Scotty dog in the toy store to find the North of my magnets, as I tend to lose track.
Mosey


Don't waste your time and money. Just wire it up and flash the sensor to find the correct pole. Then mark the magnet by painting the end with a sharpie. Press them in the disk and be done with it. That way north and south mean nothing. All you have to worry about is "this side fires the plugs" and you are 100% positive it will be correct when assembled.
« Last Edit: January 18, 2014, 10:57:56 PM by stevehuckss396 »
Do not be like the cat who wanted a fish but was afraid to get his paws wet.

Offline Tennessee Whiskey

  • Full Member
  • *****
  • Posts: 3750
  • Springfield, Tennessee. USA
Re: Hall Sensors
« Reply #16 on: January 18, 2014, 11:58:04 PM »
And I'm still trying to start a fire with a magnifying glass :lolb: :lolb:. Y'all just keep on, I'm gonna need this info someday, I know I will :ThumbsUp:

Whiskey

Offline Mosey

  • Full Member
  • ****
  • Posts: 1583
  • Rosemont, New Jersey, USA
Re: Hall Sensors
« Reply #17 on: January 19, 2014, 01:26:49 AM »
I have a couple of quick questions about your great suggestions. Hall sensors have 3 wires, when looking from the side with the beveled edges, from the left  leads 1,2,& 3 go as follows according to Jerry Howells layout: 1. goes I dont know where 2. Goes to Engine Ground,  negative, and 3. goes to 6 volt positive.
If that is correct, do all Hall Sensors have the same 3 leads?
Which do you mean is the Controlled lead, and which is the positive? (the #3?)
Just to amuse you, I include a picture of the board with it's heat sink in place on the engine, and the Roy Sholl dual coil is just above in it's holder.


Mosey


Offline stevehuckss396

  • Full Member
  • ****
  • Posts: 1367
  • Sterling Heights, MI
    • Steve's Miniature Sparkplugs
Re: Hall Sensors
« Reply #18 on: January 19, 2014, 02:18:09 AM »
Hard to say without a drawing Mosey but I'm sure all 3 go back to the little blue terminal strip. You would have to look at the schematic for which spot.
Do not be like the cat who wanted a fish but was afraid to get his paws wet.

Offline Bezalel

  • Full Member
  • ****
  • Posts: 376
  • - Skype:Bezalel2000
Re: Hall Sensors
« Reply #19 on: January 19, 2014, 03:21:35 AM »
Hi Mosey


The Bullet is looking good,


I'm curious about the configuration of the thermal connection to the heat sink.
 
Please put me straight if it is not the case, however, it appears to be that the fiberglass PCB is mounted between the the T220 package and the heat sink. This configuration can promote early component failure due to heat stress. The heat transfer to the heat sink through the bolt only, is quite limited.


It is good practice to bolt the thermal connection tab directly to the heat-sink with heat transfer compound between the two.


Fiberglass is not celebrated for it's thermal conductivity properties.


Where electrical isolation is required between the heat sink and the thermal tab of the device a mica insulator with heat sink compound on both sides of the insulator should be used.

This may have nothing to do with the failure discussed in the original question, but it is an important issue when you are looking for heat related semiconductor failure.

Bez
Queensland - wet one day, humid the next

Offline Don1966

  • Full Member
  • *****
  • Posts: 5940
  • Morgan City, LA (Along the Gulf Coast)
Re: Hall Sensors
« Reply #20 on: January 19, 2014, 03:43:11 AM »
Mosey the the no. 1 lead is positive, the no.2 lead is negative, the no.3 lead is out or controlled lead. Disconnect the Hall leads from the board and touch the terminal on the PCB where no.2 and no .3 leads connected. Just rack a jumper across the two terminal to test your PCB. This will simulate a contact closure. The Hall Sensor makes these two terminals together when it is turned on. If the sensor is shorted the board will stay on. PM if you still have problems.
Bez is correct about the Heat Sink, the transistor should be mounted on it for proper heat transfer. There should of had a flat mica insulator to mount beneath the transistor with the kit. This is to isolate the transistor from the heat sink.

Don
« Last Edit: January 19, 2014, 03:48:14 AM by Don1966 »

Offline Bezalel

  • Full Member
  • ****
  • Posts: 376
  • - Skype:Bezalel2000
Re: Hall Sensors
« Reply #21 on: January 19, 2014, 04:39:03 AM »
Mosey


I'm not familiar with this particular Circuit so hopefully you and Don can guide my comments with regard to the specifics.

Was a mica insulator supplied? If yes, there would also have to be insulating bushes for the Brass fastener or a nylon bolt and nut.
You already mentioned it worked for a little while so the need for electrical isolation isn't an issue, the inability to dissipate enough heat is a likely cause of the failure.

It looks like electrical isolation between the transistor and the heat sink is not required but if it is, then bolting the transistor to the heat sink with an uninsulated brass (conducting) fastener (as appears to be the case in the photo) is definitively a no go.

Cheers

Bez
Queensland - wet one day, humid the next

Offline Mosey

  • Full Member
  • ****
  • Posts: 1583
  • Rosemont, New Jersey, USA
Re: Hall Sensors
« Reply #22 on: January 19, 2014, 02:57:13 PM »
Bez,
Howell's instructions shows the heat-sink as "not-absolutely necessary", and only for "unusual circumstances cause it to heat up". He shows it mounted with a 2-56 pan-head screw, thru the transistor, thru the heat-sink, and to the board. "The tab is only for that purpose". So, I used a pretty gold-anodized fluted heat sink from one of my R/C speed controls and mounted it with a brass 2-56 bolt I had lying around. No insulation is called for. This contradicts what you guys are saying, so I will check with Allen Howell to verify this point.
Don,
Can't thank you enough for your explanation of the Hall sensor's lead assignments, now I can run this simple test and get on with it!
I imagine there may be 1 or 2 other guys with as little knowledge as me who could benefit from this discussion, as there is a lot of talk about Hall sensors.
The Roy Sholl dual coil is a major part of this project, so we will see it work when I get the board working.
Thanks to Steve also, Buddy.
Mosey :Doh: :stir: :happyreader:

Offline Mosey

  • Full Member
  • ****
  • Posts: 1583
  • Rosemont, New Jersey, USA
Re: Hall Sensors
« Reply #23 on: January 19, 2014, 09:37:58 PM »
I did  as suggested by Don, and there is no voltage at the 2 leads, which confirms to me that the transistor is bad. I will replace it and test again. Hopefully, that will do it. I discovered a polarity error in connecting the power,and hope not to repeat that stupid move.
In the future, I will use polarized connectors. :Doh:
Stay tuned. It is important to me to try to solve this myself, even though I have offers of expert help. :hammerbash:
Mosey

fcheslop

  • Guest
Re: Hall Sensors
« Reply #24 on: January 19, 2014, 10:38:59 PM »
Hi Mosey, Not sure but Iv a niggling feeling about the capacitor mounted on the terminal strip I seem to remember it was for point ignition and not hall switching could well be wrong as my drawings are in the shop but will have a look tomorrow evening.
The output transistor on my version is simply bolted to the heat sink with no insulator and has never been a problem.I blew both the Hall and the output transistor after loosing the engine ground :facepalm:and Iv fitted a larger diode.
I think I bought my TM6 when I bought some drawings from Mr Shores but not sure if I bought it from him it wasnt a kit just a drawing? so I built it on vero board.
Its now ran for several years
Good luck
cheers
frazer
« Last Edit: January 19, 2014, 10:42:31 PM by fcheslop »

Offline Mosey

  • Full Member
  • ****
  • Posts: 1583
  • Rosemont, New Jersey, USA
Re: Hall Sensors
« Reply #25 on: January 19, 2014, 11:03:27 PM »
The cap came with the coil from Roy Sholls and I installed it. Is it a problem? I thought these coils need a cap to work properly.
Mosey

Offline stevehuckss396

  • Full Member
  • ****
  • Posts: 1367
  • Sterling Heights, MI
    • Steve's Miniature Sparkplugs
Re: Hall Sensors
« Reply #26 on: January 19, 2014, 11:14:35 PM »
The cap came with the coil from Roy Sholls and I installed it. Is it a problem? I thought these coils need a cap to work properly.
Mosey

Hey Mosey. If Roy sent it, use it. He does a lot of testing so it's there for a reason. I doubt he would send it if it were not needed.
Do not be like the cat who wanted a fish but was afraid to get his paws wet.

Offline Mosey

  • Full Member
  • ****
  • Posts: 1583
  • Rosemont, New Jersey, USA
Re: Hall Sensors
« Reply #27 on: January 20, 2014, 12:33:31 AM »
Yes, thanks Steve, Roy knows this stuff,  and Caps are mentioned in Bob Shore's book as necessary. Cap is going to stay.
Mosey

Offline Bezalel

  • Full Member
  • ****
  • Posts: 376
  • - Skype:Bezalel2000
Re: Hall Sensors
« Reply #28 on: January 20, 2014, 01:55:10 AM »
Hi Mosey
 
Good to see your making progress.
 
 
Howell's instructions shows the heat-sink as "not-absolutely necessary", and only for "unusual circumstances cause it to heat up". He shows it mounted with a 2-56 pan-head screw, thru the transistor, thru the heat-sink, and to the board. "The tab is only for that purpose".

I might just mention the real purpose of the tab.
 
Which is to act itself as a heat sink with a large surface area ( mostly the back of the semiconductor) to disipate the heat into the air.
A small part of the surface area is sacrificed  in the form of a hole which can be used to secure the device to a bigger heat sink.
If you bolt one side of the device to a thermal insulator, it can't disipate the heat and Thermal-runaway kicks in - the kryptonite for semiconductors  -
 
These apparently small details do make a difference for semicanductor long life.
 
Howell's design obviously uses the correct size device in the circuit to disipate the heat when the transistor is standing in free air.
Covering part of the heat sink changes the rules and is like turning off the cooling fan.
 
I'm sure we all have an understanding of what happens when the fan stops working in a computer.
 
Bez
 
Queensland - wet one day, humid the next

Offline Don1966

  • Full Member
  • *****
  • Posts: 5940
  • Morgan City, LA (Along the Gulf Coast)
Re: Hall Sensors
« Reply #29 on: January 20, 2014, 02:12:55 AM »
Yes, thanks Steve, Roy knows this stuff,  and Caps are mentioned in Bob Shore's book as necessary. Cap is going to stay.
Mosey
Roy might have designed has coil around the capacitor. The capacitor and the coil act as a tune circuit to intensify the secondary voltage of the coil. So I would ask Roy if it is. New modern ignition coils no longer need it with electronic switching circuits.

Don

Offline Alan Haisley

  • Full Member
  • ****
  • Posts: 669
  • Near Clayton, North Carolina, USA
Re: Hall Sensors
« Reply #30 on: January 20, 2014, 02:32:43 AM »
Mosey,

Your picture of the circuit board looks like the circuit board is between the transistor and the heat sink. If so you won't get much heat sink value.

Also it looks like your heat sink is screwed to something which makes me wonder if the heat sink is electrically isolated from the engine and everything else. Assuming the engine frame is in the circuit somewhere the heat sink needs electrical isolation.

Alan
Near Raleigh, NC, USA

Offline Bezalel

  • Full Member
  • ****
  • Posts: 376
  • - Skype:Bezalel2000
Re: Hall Sensors
« Reply #31 on: January 20, 2014, 03:13:49 AM »
Hi Mosey
 
Alan,
 
I just visited Jerry's web page
 
well knock me over with a feather!   Jerry bolts the semiconductor directly to the circuit board.

 I guess he doesn't get daily ambient temperatures in the thirties and forties oC at his place.



 
The designer says it works and there are plenty of them out there so I guess history shows it is ok with this circuit.

Still not good practice in my view.

Bez
Queensland - wet one day, humid the next

Offline Don1966

  • Full Member
  • *****
  • Posts: 5940
  • Morgan City, LA (Along the Gulf Coast)
Re: Hall Sensors
« Reply #32 on: January 20, 2014, 03:44:18 AM »
Mosey,

Your picture of the circuit board looks like the circuit board is between the transistor and the heat sink. If so you won't get much heat sink value.

Also it looks like your heat sink is screwed to something which makes me wonder if the heat sink is electrically isolated from the engine and everything else. Assuming the engine frame is in the circuit somewhere the heat sink needs electrical isolation.

Alan
Allen your point is well taken, the collector of the transistor is usually the part attached to the transistor tab. In this circuit the collector is tied to the coil lead and the emitter is tied to positive lead this would short out the transistor.
Mosey I suggest you make sure the transistor tab is not connected to the heat sink and the engine. I can send you a mica isolator and a screw insulator insert if you want it.

Don

Offline Mosey

  • Full Member
  • ****
  • Posts: 1583
  • Rosemont, New Jersey, USA
Re: Hall Sensors
« Reply #33 on: January 20, 2014, 02:03:27 PM »
Don, I'm a little befuddled. Yes the heat sink is connected to the tab with a 2-56 brass screw, with the PCB in the middle, and then the engine frame. If not connected to the tab, it is no longer a heat sink. I can certainly isolate the HS from the engine with nylon bolts and washers, as I intended to use the HS as my mounting for the PCB. But, is the tab really connected to the circuitry of the transistor? Strange, as it is there for HS purposes. I only included the HS because it makes a nice mount and it looks cool.
To recap: Isolate the transistor and the HS from the engine, but connect them mechanically to each other for heat transmission.
I will use the Cap furnished by Roy Sholl on his coil.
New transistor is coming and will be used.
Retest as per Don.
Then, we'll see some sparks? Maybe? Hope so.
Thanks guys, really appreciate all the help.
Mosey ( out here in the darkest jungles of New Jersey) :happyreader:
             
« Last Edit: January 20, 2014, 02:08:43 PM by Mosey »

Offline Alan Haisley

  • Full Member
  • ****
  • Posts: 669
  • Near Clayton, North Carolina, USA
Re: Hall Sensors
« Reply #34 on: January 20, 2014, 03:48:52 PM »
Mosey,

I think that the tab is bonded to the transistor substrate to provide the heat sinking properties. That makes it an electrical bond as well as a thermal bond.

If it were I doing this, I would move the heat sink out. Right now it is the “third layer”: (1) transistor; (2) PC board; (3) heat sink. Make the heat sink first layer, then the transistor, etc. Also if you really want the heat sink to be effective, go to your local Radio Shack or similar store and get a small tube of thermal grease to put between the heat sink and the tab.

You may need a thicker nylon spacer to make the circuit board stand off far enough to not short anything.

Alan
Near Raleigh, NC, USA

fcheslop

  • Guest
Re: Hall Sensors
« Reply #35 on: January 20, 2014, 04:06:55 PM »
Thanks for the cap info.
cheers

Offline Mosey

  • Full Member
  • ****
  • Posts: 1583
  • Rosemont, New Jersey, USA
Re: Hall Sensors
« Reply #36 on: January 20, 2014, 07:01:31 PM »
The Cap supplied by Roy and in my circuit is a 104K, 400v.
Mosey

Offline Don1966

  • Full Member
  • *****
  • Posts: 5940
  • Morgan City, LA (Along the Gulf Coast)
Re: Hall Sensors
« Reply #37 on: January 20, 2014, 07:48:03 PM »
Yes! the collecter is connected to the transistor tab and is there for heat transfer to the heat sink if one is used or just as a heat sink itself. You can mount the heat sink and the transistor together as long as you isolate it from the frame you should be ok. This explains way you blew your transistor.

Regards Don

Offline Bezalel

  • Full Member
  • ****
  • Posts: 376
  • - Skype:Bezalel2000
Re: Hall Sensors
« Reply #38 on: January 20, 2014, 09:08:09 PM »
Hi Mosey
 
Isolating the transistor from the engine can be done in two places,
 
 
              a.  a mica insulator between hestsink and transistor, with insulated bolting hardware
              b.  insulate the heatsink from the engine with insulated bolting hardware
 
you can do both, but if you chose to do one only, use the first method so you don't have a live heat sink, the circuit will still work but not a good thing
 
If you use option b. only, any conducting object that touches the engine and heatsink at the , same time will short out the transistor again. 
 
Bez
Queensland - wet one day, humid the next

Offline Mosey

  • Full Member
  • ****
  • Posts: 1583
  • Rosemont, New Jersey, USA
Re: Hall Sensors
« Reply #39 on: January 20, 2014, 10:07:36 PM »
I think I understand this now, I will insulate the PCB from the Heat Sink with a non-conducting fastener, nylon washer, using proper thermal grease, and the Heat sink from the engine via non-conducting stand-offs (make em from nylon)  and fasteners (nylon).
See pictures below which mayt shed light on what I have. The existing brass standoffs and fasteners will be replaced.
Mosey




By the way, the blue plastic binding strips only allow a #16 wire, so that limits the ground wire back to the engine/coil.

« Last Edit: January 20, 2014, 10:24:07 PM by Mosey »

Offline Don1966

  • Full Member
  • *****
  • Posts: 5940
  • Morgan City, LA (Along the Gulf Coast)
Re: Hall Sensors
« Reply #40 on: January 20, 2014, 10:38:31 PM »
Look good Mosey, I suggest you buy some nylon fastners to go with your new insulators. You wouldn't want to put the screws back into in unless your insulators had isolators to isolate the screws with.

regards Don

Offline Mosey

  • Full Member
  • ****
  • Posts: 1583
  • Rosemont, New Jersey, USA
Re: Hall Sensors
« Reply #41 on: January 20, 2014, 10:39:50 PM »
Don,
Absotutely!
Mosey

Offline Bezalel

  • Full Member
  • ****
  • Posts: 376
  • - Skype:Bezalel2000
Re: Hall Sensors
« Reply #42 on: January 20, 2014, 10:50:38 PM »
Great Mosey
 
Don't forget the mica insulator between Transistor and heatsink.
 
The heatsink grease is non-conductive sure but it is also a poor dielectric.
 
Which means any voltage between Transistor and heatsink will break down the very thin layer of grease. This will cause a short out between Transistor and heatsink.
 
The voltage refered to will occurr any time a tool  touches both heatsink and engine at the same time, even though the heat sink is normally isolated from the engine.

you don't wan't the engine stopping ... just coz you dropped your screwdriver on the heatsink. 
 
Bez
 
« Last Edit: January 20, 2014, 11:00:59 PM by Bezalel »
Queensland - wet one day, humid the next

Offline Mosey

  • Full Member
  • ****
  • Posts: 1583
  • Rosemont, New Jersey, USA
Re: Hall Sensors
« Reply #43 on: January 20, 2014, 11:14:15 PM »
Would a nylon washer be acceptable between HS and PCB? I don't have any mica.

Funny you should mention contact with the system, as I ponder the practicality of the exposed ignition. Is it a problem to leave it hanging out in the open, exposed to fingers or bumping into? Consider housing the ignition PCB in a plastic shield? Cooling?
Or is this overthink?
You know I hate those ignitions buried in a wooden coffin underneath the engines.
Mosey

Offline Don1966

  • Full Member
  • *****
  • Posts: 5940
  • Morgan City, LA (Along the Gulf Coast)
Re: Hall Sensors
« Reply #44 on: January 20, 2014, 11:28:46 PM »
Mosey you need something like this. The top slides open and all the connections are on the box.  :stickpoke:

Don

Offline Mosey

  • Full Member
  • ****
  • Posts: 1583
  • Rosemont, New Jersey, USA
Re: Hall Sensors
« Reply #45 on: January 21, 2014, 12:10:24 AM »
Don,
Exactly what I don't want...to hide the components in a box! I want people to see the stuff because I think it adds to the interest in the engine systems.
But thanks!
Mosey

Offline Alan Haisley

  • Full Member
  • ****
  • Posts: 669
  • Near Clayton, North Carolina, USA
Re: Hall Sensors
« Reply #46 on: January 21, 2014, 12:14:22 AM »
Would a nylon washer be acceptable between HS and PCB? I don't have any mica.

Funny you should mention contact with the system, as I ponder the practicality of the exposed ignition. Is it a problem to leave it hanging out in the open, exposed to fingers or bumping into? Consider housing the ignition PCB in a plastic shield? Cooling?
Or is this overthink?
You know I hate those ignitions buried in a wooden coffin underneath the engines.
Mosey

Some place like Radio Shack would probably have the mica washers. If you want the heat sink to actually function you can't depend on the nylon washer. The mica washers are both much thinner and better by far heat conductors than the nylon.
You might build a rectangular tube out of big box store clear acrylic plastic. That way only the ends would be exposed at all and the parts would all be still nicely visible.

Alan
Near Raleigh, NC, USA

Offline Mosey

  • Full Member
  • ****
  • Posts: 1583
  • Rosemont, New Jersey, USA
Re: Hall Sensors
« Reply #47 on: January 21, 2014, 12:28:15 AM »
I might be able to find some mica in an old appliance that used heat like an iron or printer. I'll find it.
I could machine a plastic gem box to fit.Thanks,
Mosey

Offline Bezalel

  • Full Member
  • ****
  • Posts: 376
  • - Skype:Bezalel2000
Re: Hall Sensors
« Reply #48 on: January 21, 2014, 12:32:10 AM »
Would a nylon washer be acceptable between HS and PCB? I don't have any mica.

Hi Mosey
 
short answer is no.
 
The mica insulator provides electrical isolation between transistor and heatsink.
At the same time provide good thermal conductivity.
 
Mica, nylon & PVC all are good electrical insulators but mica has good thermal conductivity, nylon & PVC don't
link below is an example of mica washer for T220 transistor, a very thin slice of mica 15mm x 19mm with a 3.6mm hole for the screw.
 
http://uk.farnell.com/multicomp/mk3306/insulating-kit-mica-to-220/dp/520214
 
Bez
Queensland - wet one day, humid the next

Offline Don1966

  • Full Member
  • *****
  • Posts: 5940
  • Morgan City, LA (Along the Gulf Coast)
Re: Hall Sensors
« Reply #49 on: January 21, 2014, 12:35:54 AM »
Mosey you want me to send you some mica insulators ?

Don

Offline Mosey

  • Full Member
  • ****
  • Posts: 1583
  • Rosemont, New Jersey, USA
Re: Hall Sensors
« Reply #50 on: January 21, 2014, 01:22:42 AM »
Yes, Don, please do. I found mica sheets at Amazon for repairing microwaves, but as you know I only need a couple of small washers, to fit 8-32 bolt.
I'll PM my address.
I'm making the standoffs from nylon rod, to fit 4-40 nylon bolts I will make. This is fun!
Mosey

PM Sent

Offline Mosey

  • Full Member
  • ****
  • Posts: 1583
  • Rosemont, New Jersey, USA
Re: Hall Sensors
« Reply #51 on: January 21, 2014, 04:25:23 PM »
I have remounted the HS onto the front of the PCB, instead of the rear, with a non-conducting screw, and it awaits a mica washer to insulate.Now that the HS is not in the circuit, can it be fastened to the engine with conducting fasteners? (can't find 4-40 screws in nylon) but  I will make them if I must.


Soon as I get the replacement transistor, were ready to fire. :zap:
Mosey

Offline Alan Haisley

  • Full Member
  • ****
  • Posts: 669
  • Near Clayton, North Carolina, USA
Re: Hall Sensors
« Reply #52 on: January 21, 2014, 06:36:29 PM »
Microfasteners has nylon 4-40 screws if you decide you need some.

Alan
Near Raleigh, NC, USA

Offline Mosey

  • Full Member
  • ****
  • Posts: 1583
  • Rosemont, New Jersey, USA
Re: Hall Sensors
« Reply #53 on: January 21, 2014, 07:14:15 PM »
Alan,
Thank you, will do. Homestretch, you know!
Mosey

Offline Don1966

  • Full Member
  • *****
  • Posts: 5940
  • Morgan City, LA (Along the Gulf Coast)
Re: Hall Sensors
« Reply #54 on: January 21, 2014, 07:29:21 PM »
Mosey your insulator is in the mail. I have also included a replacement transistor. Most transistor that are in package have the insulator for the transistor and screw.

Don

Offline Mosey

  • Full Member
  • ****
  • Posts: 1583
  • Rosemont, New Jersey, USA
Re: Hall Sensors
« Reply #55 on: January 21, 2014, 08:01:52 PM »
Thank you, Don. I'll probably turn it right around and send  it to you to make it work. We're getting 6-10 " of snow right now, so down to the basement I go.
Regards,
Mosey