My transistor ignition and tachometer project (TigTac)

[Stuart]

Paul
You are doing a great project and your log is very informative although I am reasonable with electronics ( built a computor from descreat components befor the snicker z80 using the zilog Z80) I am not up with the pic and its programming , normal programming is ok C and swift .

The only comment I will make but do not take offence not every one uses windows an do not have a pc in the house eg I only have macs , and I do not intend buying windows to run in boot camp
Is there a BT app to talk to your device

Stuart

[PStechPaul]

I know next to nothing about Apple products but I'm sure they must have Bluetooth as well as some sort of serial terminal program.

Some links:
http://support.apple.com/kb/PH6560
https://discussions.apple.com/thread/5295159?start=0&tstart=0
https://itunes.apple.com/us/app/pterm-ssh-telnet-client-terminal/id287269552
http://todbot.com/blog/2006/02/23/howto-mac-os-x-bluetooth-serial-port/ (Looks like Apple MACs use something called Zterm)
http://soft.udm4.com/downloading/apple_bluetooth_serial_terminal_android/
http://www.macupdate.com/app/mac/31352/coolterm (Free download)
https://itunes.apple.com/us/app/get-console/id412067943 ($10 Apple app)

You can also use a serial terminal app for an iPhone or iPad or an Android hand-held or tablet device.

Also, I'm pretty sure that MACs have a Windows emulation mode, so if I wrote a Windows GUI you could still use it.

[Stuart]

Thanks Paul

I will take a look but as apple have changed a lot with 10.10.x I am not sure

As to the emulation mode that's not there in any form because they would have to use microsofts api and pay a licence

Yes you can run windows native ,no emulation under boot camp but then you have to by a full copy of windows , VMware and parallels will do it on top of OS X but again you have to buy windows

I will post a request for info on the apple dev forum ( private for Apple Devs) which I am for testing OS X beta seeds , and for dev of software , but nothing like that you do

[PStechPaul]

I have just finished building and preliminary testing of the transistor drive portion of the circuit. I used a BUJ403A NPN BJT which is rated 1200V and 6A, and I am driving it through a 10 ohm resistor from an MJE170 PNP transistor with a 200 ohm base resistor. I was able to get a pretty fat spark at 6 VDC and a probably adequate spark at 3 VDC. I have a 0.47 ohm power resistor in series with the 1.4 ohm coil, which limits the current to about 3 amps at 6 volts. For 12 volt operation, this would need to be about 3 ohms and would dissipate about 22 watts. For model engines, probably 6 volts would be perfect, but perhaps it would good to be able to use a single 3.3V LiFePO4 cell or 3.7V Li-Ion.

I'll put together a better demo and take some video later, hopefully with the TigTac circuit connected. Then it will just be a matter of arranging for some user I/O to set parameters and read RPM, which is mostly software.

When I first started testing, it worked a few times and then the coil current turned on solid. I thought the transistor or another component had shorted, but actually I had neglected to disconnect the points from the original demo, and somehow they were not initially making contact. A piece of tape on the points was all that was needed.

I also need to make the cam and crank to operate the points, but it might be better to rig up an inductive proximity sensor and/or an optical system. The conventional points have a rather strong spring, and I think it would be better to use an electronic sensor on small model engines. What do most of you use? If you could send me a spare ignition set-up, it would help me tailor it to that purpose. I'll have it set up and working at Cabin Fever, so you can see it there and retrieve your mechanisms there, or I can return them.

[PStechPaul]

I have finally finished building the TigTac into an enclosure about 7.5"W x 4.5"D x 2.5"H. It has a 6V SLA battery inside, with an on/off switch to a pair of binding posts. There is another set of binding posts for connecting the generator (0-30 VDC), and a 3 digit LED panel meter to read either battery voltage or generator voltage, as selected by a switch.
 
The TigTac circuit with the PIC16F1825 drives a 16 character by two-line LCD display, which shows dwell and RPM as measured by contact closure or an inductive proximity sensor, which plugs into a DIN connector (from an old PC keyboard). There is also a Bluetooth module which sends the information, as well as running time, to a terminal emulator program on a PC for display. It took me a couple of days to figure out why the Bluetooth serial connection was not working properly.
 
The circuit is supposed to provide a signal to the coil circuit to generate a spark with programmable delay or advance, but I have not yet implemented it. However, I do have the circuit mounted on a board and it can be manually triggered with a pushbutton or mechanical points, and possibly also with the proximity sensor. I have also added a 200M high voltage resistor and a 20k resistor to ground, which may be used to measure and observe the coil primary voltage waveform on a scope. This is a 10,000 to 1 ratio so it could even be used for the spark voltage itself. I may play with that later.
 
I'll have these "toys" with me at Cabin Fever, and I'll be happy to discuss the technical details. I'll even bring my laptop computer which can show the information from the TigTac, and I'll have the Microchip PicKit 3 so I can show how it can be used to customize and enhance the operation.

[stevehuckss396]

Are there any pictures? did you use a mini coil or a conventional aoutomotive coil? How small is the total package?  I like the auto advance feature and am curious how well it works.

[PStechPaul]

I'll be taking pictures of everything at Cabin Fever, but now I'm just trying to get everything done and put together well enough to take and show. I am using a conventional large automotive coil, but it should work with anything. The ignition advance is something that will need to be designed. If the points or sensor are set so that they close and open before the point of maximum advance, then the circuit can provide a programmable delay, but if they are set at TDC, then the circuit would have to read the RPM and then calculate when to charge the coil and then create the spark. Actually, that would be necessary in any case, unless there were a true position sensor to read the actual degrees independent of speed. The speed probably will not change a whole lot from one revolution to the next, except perhaps when starting. I don't have a model ICE to test it on, but maybe I'll get more info from people at CF, and possibly even maybe borrow one to use as I develop this device.