I've tried using the 555 to switch my HV source on and off - it does not work.

I'm surprised. What was the 555 frequency? Can you post a schematic showing exactly how you wired the 555 to the module?

I tried using a 1uF cap... the circuit does not turn off fast enough.

Are you merely checking the output cap voltage? If so, and the only discharge path is the 1meg bleed resistor across it then no, it definitely wouldn't seem fast enough (~1 sec). But what is important is does the cap charging cease almost immediately (it should, within one oscillation cycle, ~ 3 microseconds) ?

 

OK - You guys convinced me to go get one of the GM HEI modules. see back posts... my only questions are:

1. 4 pin or 7 pin version?
2. Do you think my trigger coil will be enough to fire it?

- Mark


PS: I'm off to the auto parts store after work... I'd appreciate your feedback before I leave in about 30 mins.

 

Alec - if you want, I can send you one of these power boards to tinker with. I wired up the 555 just like Irving showed me. I added an inverter chip on the output too so that I can have a pulse up and a pulse down if I needed it.

 

is there any way to get a signal generator circuit that I could make that looks like the output of my trigger coil and magnet? is there a signal generator that can look at a signal and replicate it?

 

Alec - if you want, I can send you one of these power boards to tinker with.

Thanks, but international shipping to the UK would make that a very expensive option.

is there any way to get a signal generator circuit that I could make that looks like the output of my trigger coil and magnet?

It could no doubt be done, if we knew the coil's inductance, resistance and relationship between output voltage, rpm and radius of rotation of the magnet; but can't you just use the coil and magnet on a temporary jig?

 

Thanks, but international shipping to the UK would make that a very expensive option.

It could no doubt be done, if we knew the coil's inductance, resistance and relationship between output voltage, rpm and radius of rotation of the magnet; but can't you just use the coil and magnet on a temporary jig?

yes - that's what I'm going to do.

what HEI module do you recommend?

do you know if the HEI module can be triggered by my magnet / coil?

 

yes - that's what I'm going to do.

what HEI module do you recommend?

do you know if the HEI module can be triggered by my magnet / coil?

i probably need something in a waterproof housing so that it can be close to the spark plug.

 

I was looking at the spec for those HEI modules. Its not obvious that there is any HV capacitive discharge in there?

 

I was looking at the spec for those HEI modules. Its not obvious that there is any HV capacitive discharge in there?

So I get a DC CDI cube big enough for my spark plug. Not one made for a 50 cc moped.

 

I was looking at the spec for those HEI modules. Its not obvious that there is any HV capacitive discharge in there?

No they fire a commonly available ignition coil.

 

OK - You guys convinced me to go get one of the GM HEI modules. see back posts... my only questions are:

1. 4 pin or 7 pin version?
2. Do you think my trigger coil will be enough to fire it?

- Mark


PS: I'm off to the auto parts store after work... I'd appreciate your feedback before I leave in about 30 mins.

One of the best HEI off use pages lots of information about the differences in them and how to use them.
http://gpzweb.s3-website-us-east-1.amazonaws.com/Ignition/GPZheiModForPoints.html

To my pea brain you trigger coil looked like an old solenoid coil with a bolt through it. If you have the magnet on the flywheel why not use a Hall sensor or get an old HEI distributor and pull the trigger from it? If you spend some time with Google there are many ways of doing what your trying to do.

 

Question: can you guys find a part that is obsoleted in all of my circles?
Bourns Inc. M8104CT-ND also known as PM61300-5-RC



Could this work:

PM61300-5-RC PM61300-5-RC

or this?

Wurth: 750314597

 

I've no experience of any of those transformers, but I note the Wurth: 750314597 is specified for a buck converter, not a boost converter. The primary voltage is rated 10-40V, but it is unclear whether the secondary winding would cope with 350V.

 

is there any way to get a signal generator circuit that I could make that looks like the output of my trigger coil and magnet?

The circuit below would give a rough approximation of the trigger coil output; hopefully good enough for testing purposes. Pulse amplitude is intentionally limited to about 0.5V for a 'worst case' test.
Pulse repetition period (again 'worst case') is about 100mS with the R4/C1components shown. If the HV module could recharge 1uF to 350V within that period after being blanked it should be ok to use in your application.

 

The circuit below would give a rough approximation of the trigger coil output; hopefully good enough for testing purposes. Pulse amplitude is intentionally limited to about 0.5V for a 'worst case' test.
Pulse repetition period (again 'worst case') is about 100mS with the R4/C1components shown. If the HV module could recharge 1uF to 350V within that period after being blanked it should be ok to use in your application.

View attachment 276183

Thanks Alec

 

Let me ask you something...
what is the difference between the prefix and suffix letters around a 555 timer?

I have an NE555P, I also have a chip labeled 555 from Texas Instruments, then I have another labeled LM555CN

I can't find any differences. Does one have a pulse up and the other inverted?

I have the same kind of question for opto-isolators. I see a circuit call for 4N36 and I only have 4N28, 4N35 and 4N45

 

what is the difference between the prefix and suffix letters around a 555 timer?

As with most ICs, the prefix generally indicates the manufacturer and the suffix indicates the revision level or the package type (e.g DIL, SOIC etc).
For the opto-isolators the numerals indicate such parameters as sensitivity, maximum current rating etc. Check their datasheets and compare.
If you ever design a circuit you should always check and understand the datasheet of any component you intend to use.

 

You guys have any sources for obsolete parts? Is there any way to find out what a component may have been used in?

Have either of you heard of a mosfet labeled AO1510? I can’t find a. Umber like that anywhere

 

Question: can you guys find a part that is obsoleted in all of my circles?
Bourns Inc. M8104CT-ND also known as PM61300-5-RC



Could this work:

PM61300-5-RC PM61300-5-RC

or this?

Wurth: 750314597

The Bourns PM61300-5-RC is intended for Cold-Cathode Fluorescent Lights (CCFL) ie backlights etc. Its 10v primary & 1300v/70mA secondary.

There are stockists of obsolete parts but they generally have minimum order quantities of 100 or their complete stock level...

The Wurth 750314597 is only .:1.5 turns ratio intended for 10-40v in, 15.5v out, so no good.

There are few transformers in the Wurth catalog that are 400v in, 6 - 12v out for offline switchmode power supplies. One or two of them might work backwards well enough to meet this need; I'll let you know.

 

Ok. I did find a distributor that had (4) of these transformers for $260 USD. Insane.

if I can find a comparable transformer I think I’ll have a circuit to share.