'82 450 Igniter - Repair, Replace, or Make?

[pete]

Hahaha I think it's quite funny...

[rustybronco]

Pete,

If the input of the HEI module requires a input that's 180 degrees out of phase from the stock system and you need voltage gain as well, how about making an inverting amplifier out of an Op amp?

http://www.technologystudent.com/elec1/opamp2.htm

http://www.wisc-online.com/objects/ViewObject.aspx?ID=SSE2903

[Matchless]

Pete,
Dale has a very good suggestion with using an op-amp and it is even easier than a transistor seeing you have a breadboard. If I can suggest:

1) Test what polarity with the 1.5v battery fires the HEI, that should give you an idea as to whether it needs the positive going or negative going part of the pulse.
2)You need to swing the motor with the starter to measure the amplitude of the pulse from the pickup. By hand is too slow. Or pull the pickups off the bike and swing the magnet past it fast by hand.
3) The pulse on top of the "bias" voltage should lift the pulse into the range of 1.45 to 1.65V to fire the HEI. (I am using the figures you quoted)
4) The bias voltage must stay under 1.37V to allow the HEI to switch off properly between pulses otherwise you may experience "ghost" sparks which can be seen with a timing light.
5) The op-amp power feed should have some sort of regulation, zener or VR and smoothing capacitors for the final product before installing it on the bike. For testing a battery not under charge may not need this.

Now that you have a scope handy you can actually see what is happening or not happening!

Once you solve this problem, you are going to help many people as the GS450 ignitors seem to fail quite easily.

[pete]

Pete,

If the input of the HEI module requires a input that's 180 degrees out of phase from the stock system and you need voltage gain as well, how about making an inverting amplifier out of an Op amp?

http://www.technologystudent.com/elec1/opamp2.htm

http://www.wisc-online.com/objects/V...spx?ID=SSE2903

Hmmm good point there Dale, and the "LM741" is ringing a very faint bell for me. I'm sure I used them for something sometime but that was far too long ago now.

The signal required for the OEM ignitor spark is definitely positive. The test says connecting the positive lead of the multimeter to the pickup coil connector should generate the spark, rather than saying taking it away generates the spark.

I'm really regretting not keeping up with the electronic fiddling I used to do now.

Anyway, my only question with the op amp is cost vs. the transistor and speed of response, so I'll find some technical data and see how it is in comparison. I don't think price will be an issue.

Pete,
Dale has a very good suggestion with using an op-amp and it is even easier than a transistor seeing you have a breadboard. If I can suggest:

1) Test what polarity with the 1.5v battery fires the HEI, that should give you an idea as to whether it needs the positive going or negative going part of the pulse.
2)You need to swing the motor with the starter to measure the amplitude of the pulse from the pickup. By hand is too slow. Or pull the pickups off the bike and swing the magnet past it fast by hand.
3) The pulse on top of the "bias" voltage should lift the pulse into the range of 1.45 to 1.65V to fire the HEI. (I am using the figures you quoted)
4) The bias voltage must stay under 1.37V to allow the HEI to switch off properly between pulses otherwise you may experience "ghost" sparks which can be seen with a timing light.
5) The op-amp power feed should have some sort of regulation, zener or VR and smoothing capacitors for the final product before installing it on the bike. For testing a battery not under charge may not need this.

Now that you have a scope handy you can actually see what is happening or not happening!

Once you solve this problem, you are going to help many people as the GS450 ignitors seem to fail quite easily.

Agree Andre, it is a good idea.

I definitely need to get the motor cranking with the starter. I was hoping I could leave that until I'm ready to kick it over for the first time, but that's not going to work.

Also, I've already confirmed with the AA battery that the negative pulse is required to turn the coil back off via the HEI module and fire the spark.

The only alternative is to build a test rig like Lou did but I don't have the resources for that, or at least not a suitable motor like he has to spin the governor up to a reasonable speed.

So I think my next priority is to get some oil so I can crank it and see what the signal is doing without being grounded and also to look into the LM741 op amp some more.

Thanks again guys, we'll get this nutted out in no time.

And also Andre, yes I want to get something that other 450 owners can easily use as it's about time I was able to contribute something back to the forum rather than just receiving assistance.

[pete]

Turns out the only Dick Smith near me in the city here doesn't have op amps or 47K resistors and I won't get to Jaycar until at least this weekend, so I ordered two LM741 op amps and an assortment of resistors from the Jaycar online store today. They should be here tomorrow, but it's our wedding anniversary so don't expect I'll be doing much until at least Wednesday night.

The house mate is picking up some oil for me this avo too hopefully so I should be able to give it some cranks next time I'm looking at it.

[pete]

Wedding anniversary today, so nothing doing with the ignition stuff, however I did receive my package from Jaycar with a lot of resistors and a couple of LM741 op amps in it.

I also did take 5 minutes to put the oil in today as well so I can crank it next time I'm working on it.

Fingers crossed I'll get some time tomorrow night.

[bakalorz]

Wedding anniversary today, so nothing doing with the ignition stuff, however I did receive my package from Jaycar with a lot of resistors and a couple of LM741 op amps in it.

I also did take 5 minutes to put the oil in today as well so I can crank it next time I'm working on it.

Fingers crossed I'll get some time tomorrow night.

I've only been sporadically following this thread, but have some thoughts on what I read today ... FWIW

I think that if you are worried about the timing, an opamp is probably the wrong way to go. a pure transistor stage is likely to be MUCH faster than most opamps.

For that matter I don't think you can get the 741 to work at all.
(Well, If you had to, as matter of life and death, or to win a big enough bet, you probably could by playing games with level shifting and stuff ... but not without a boatload of agravation)
For an opamp you will have to set up a proper positive AND NEGATIVE supply voltage. There are single supply opamps that will work with the bikes ground being the negative rail and can operate near it. The 741 is NOT one of them, it would need something like 12 volts, ground and MINUS 12 volt supplies.

If you MUST use an opamp, something like the LM324 will work better.
it can operate with both the inputs and output being near ground.
(if you cant get the 324 easily, search for "single supply opamp" to find others that would be ok. after you find a possible candidate, find and read its datasheet by googling the part # and pdf for example "lm324 pdf" for this one)

All the above said, I think a single transistor amp is likely to work better, and be much easier to get working correctly.

Also, don't forget that a single transistor amplifier produces an inverted output by default (which seems to be what you need)

I suspect that with the correct biasing a single bipolar NPN transistor amplifier would work well.

If it were me messing with it, thats what I would use.

To set the biasing, feed the search term "transistor biasing tutorial" into google, one of those should work.

[pete]

I've only been sporadically following this thread, but have some thoughts on what I read today ... FWIW

I think that if you are worried about the timing, an opamp is probably the wrong way to go. a pure transistor stage is likely to be MUCH faster than most opamps.

For that matter I don't think you can get the 741 to work at all.
(Well, If you had to, as matter of life and death, or to win a big enough bet, you probably could by playing games with level shifting and stuff ... but not without a boatload of agravation)
For an opamp you will have to set up a proper positive AND NEGATIVE supply voltage. There are single supply opamps that will work with the bikes ground being the negative rail and can operate near it. The 741 is NOT one of them, it would need something like 12 volts, ground and MINUS 12 volt supplies.

If you MUST use an opamp, something like the LM324 will work better.
it can operate with both the inputs and output being near ground.
(if you cant get the 324 easily, search for "single supply opamp" to find others that would be ok. after you find a possible candidate, find and read its datasheet by googling the part # and pdf for example "lm324 pdf" for this one)

All the above said, I think a single transistor amp is likely to work better, and be much easier to get working correctly.

Also, don't forget that a single transistor amplifier produces an inverted output by default (which seems to be what you need)

I suspect that with the correct biasing a single bipolar NPN transistor amplifier would work well.

If it were me messing with it, thats what I would use.

To set the biasing, feed the search term "transistor biasing tutorial" into google, one of those should work.

Thanks for that Martin.

I'm far too rusty with all my electronics theory to even pretend to remember how to set op amps up, so good to know whether I should or shouldn't go down that path. Speed of response was one question I had with them, but I ended up needing to order from Jaycar before I had time to look closely at the specs.

They're cheap enough that I'm not concerned if I don't use them, but I think I did see LM324's on the Jaycar site as well.

Either way, I have lots of BC547 transistors sitting around, I was just missing a lot of resistor values that I now have.

Thanks for the links too, that'll be very helpful along with Lou's web page on his GPZ and the CB HEI setups.

I also think I've forgotten to put a link in here to Lou's site, so here it is:

http://www.geocities.ws/loudgpz/

[bakalorz]

Thanks for that Martin.

I'm far too rusty with all my electronics theory to even pretend to remember how to set op amps up, so good to know whether I should or shouldn't go down that path. Speed of response was one question I had with them, but I ended up needing to order from Jaycar before I had time to look closely at the specs.

They're cheap enough that I'm not concerned if I don't use them, but I think I did see LM324's on the Jaycar site as well.

Either way, I have lots of BC547 transistors sitting around, I was just missing a lot of resistor values that I now have.

Thanks for the links too, that'll be very helpful along with Lou's web page on his GPZ and the CB HEI setups.

I also think I've forgotten to put a link in here to Lou's site, so here it is:

http://www.geocities.ws/loudgpz/

I looked at Lou's site and have a more detailed answer to what I would try.

Using Fig 1 on his HEI for points page:
connect everything to the right of the transistor as shown.
Use an R1 of 4.7k as shown.
Replace where he shows points with a resistor about 100 to 470 ohm. (we'll call this resistor R2)
Also connected to the base of the transistor: a capacitor with the other end of the capacitor connected to the pickup coil. At least 1 uf, bigger is probably better.

Note, while setting the operating point, disconnect the coils so they dont overheat.
To set the operating point (and dwell), adjust the ratio of resistors R1 and R2 ... for the coil to be off, the transistor should be turned on, with the base above about 0.7 volts.
Use your multimeter to measure the voltage at point G on the HEI module as you try various values of R2.
with R2 = 470, point G should be near ground.
with R2= 100, point G should be high (well above 1.65 volts anyway)
try various values of R2, Use the smallest one that still keeps G near ground (i.e. will result in coils being off when not getting signals from the pickup)
If this results in too much dwell, increase R2

To test for spark and correct assembly/bias, hook up coils, and briefly short R2 (i.e. short the transitor base to ground), when you break the short, the spark should occur.
If it passes this test, try it with the pickup and a magnet.


IF you really get a negative signal from the pickup(and it going positive again signals the spark) this should work.

If you really get a positive signal but still need amplification, a second transistor stage would be required.

[pete]

I looked at Lou's site and have a more detailed answer to what I would try.

Using Fig 1 on his HEI for points page:
connect everything to the right of the transistor as shown.
Use an R1 of 4.7k as shown.
Replace where he shows points with a resistor about 100 to 470 ohm. (we'll call this resistor R2)
Also connected to the base of the transistor: a capacitor with the other end of the capacitor connected to the pickup coil. At least 1 uf, bigger is probably better.

Note, while setting the operating point, disconnect the coils so they dont overheat.
To set the operating point (and dwell), adjust the ratio of resistors R1 and R2 ... for the coil to be off, the transistor should be turned on, with the base above about 0.7 volts.
Use your multimeter to measure the voltage at point G on the HEI module as you try various values of R2.
with R2 = 470, point G should be near ground.
with R2= 100, point G should be high (well above 1.65 volts anyway)
try various values of R2, Use the smallest one that still keeps G near ground (i.e. will result in coils being off when not getting signals from the pickup)
If this results in too much dwell, increase R2

To test for spark and correct assembly/bias, hook up coils, and briefly short R2 (i.e. short the transitor base to ground), when you break the short, the spark should occur.
If it passes this test, try it with the pickup and a magnet.


IF you really get a negative signal from the pickup(and it going positive again signals the spark) this should work.

If you really get a positive signal but still need amplification, a second transistor stage would be required.

Thanks again Martin, this is great stuff.

John and I didn't go into this much detail while chatting on Sunday, but he definitely advised going down the same path as you're suggesting here, so it's good to see we have multiple people on the same wavelength here.

I sort of understand where you're going with this and I believe I should have suitable capacitors around too, but I'll check hopefully tonight.

I'll give this a go and report back on the results.

[pete]

Really short on time tonight as I'm on call and am expecting to be called in about 2 1/14 hours to do some work and wanna get a nap in first.

Lots of resistors and the possibly extraneous LM741's



I ducked down to do some cranking, and it was hard to get a consistent signal as I didn't want to crank for too long due to the noise.

Couldn't get a decent result with the black/white common wire grounded, but I got this with the scope just across the one coil:



Same type of waveform as cranking by hand gave me, but a lot higher amplitude at 89mV.

I really need to get some daytime time to get cranking without any need to worry about noise.

Martin, hopefully tomorrow night I'll have some more time to try your suggestions as that's what I really wanted to get to tonight but didn't quite have time.

[bakalorz]

Really short on time tonight as I'm on call and am expecting to be called in about 2 1/14 hours to do some work and wanna get a nap in first.

Lots of resistors and the possibly extraneous LM741's



I ducked down to do some cranking, and it was hard to get a consistent signal as I didn't want to crank for too long due to the noise.

Couldn't get a decent result with the black/white common wire grounded, but I got this with the scope just across the one coil:



Same type of waveform as cranking by hand gave me, but a lot higher amplitude at 89mV.

I really need to get some daytime time to get cranking without any need to worry about noise.

Martin, hopefully tomorrow night I'll have some more time to try your suggestions as that's what I really wanted to get to tonight but didn't quite have time.

Your scope capture looks like a positive waveform, so I suspect you don't want to invert it. so, if you need amplification you would use two stages and invert it twice.

attached is a schematic with both versions, the top one is the inverting amp,
the bottom one is non inverting.

The resistance of R2 that my simulator says is about right (assuming a generic transistor) is about 280 ohms FWIW

I also showed an optional R3, it shouldn't be needed, but if you cant get it to work right by adjusting R2 or R7, try adding it

[bakalorz]

Your scope capture looks like a positive waveform, so I suspect you don't want to invert it. so, if you need amplification you would use two stages and invert it twice.

attached is a schematic with both versions, the top one is the inverting amp,
the bottom one is non inverting.

The resistance of R2 that my simulator says is about right (assuming a generic transistor) is about 280 ohms FWIW

I also showed an optional R3, it shouldn't be needed, but if you cant get it to work right by adjusting R2 or R7, try adding it

trying a better attachment

[pete]

Thanks again Martin, I'll endeavour to get something wired up tonight and start having a look.

One thing I know for sure is I need to invert the signal as the HEI module fires off the negative going signal. I have verified this by putting a 1.5v AA battery across the W to G terminals on the module.

[john82q]

Go with R3

Pete ,

Bakalorz's inverting amp is what you want, it s a more elegant version of what i was doodling the other day.

I am wondering about the HEI input, does it withstand 12V? I woulds use the r3 .

john