Help I am looking for a replacement for a Texas Instruments transistor part number TL170C. I am trying to repair a solid state ignition module that I have. It has several problems but I am able to locate those components.
I was able to find a data sheet on the silicon hall-effect switch but am unable to locate a replacement.
Any ideas?

thanks

Jay

 

Look at the available devices and try to find one with as close characteristics as possible to the TL170C.
Here's some, for example.
If you find one that seems close but you have a question about, post it back here.

 

This https://www.utsource.net/sch/tl170c is my goto source. They are usually pretty good.

 

To me it sounds like something you'll find on a modern lawn mower. Modern because older models used breaker point ignition. These days the ignition module is fully contained with - I believe - is a hall effect transistor that switches (fires) the ignition as the magnet passes the magneto. I see lawn mowers in the metal recycling yards all the time. If your timing is right you might be able to pick up a lawn mower from the scrap yard for 35 cents on the pound. My neighborhood has a local news organization that runs a page similar to CraigsList. I see lawn mowers there all the time. Especially at the first of the grass cutting season because people fail to drain the gasoline and properly winterize their mowers. Come the spring time they won't start. So often they get scrapped when all they really need is a carburetor cleaning. THAT is where you're going to LIKELY find a magneto with a hall effect in it. Maybe if you told us a little more about your ignition module and what it's used on. Or how you're trying to use it.

You said several issues; I'm guessing at least two issues but probably not much more. But it's just a guess.

[edit] I picked up a pressure washer pump for my pressure washer. The motor had seized up but the pump was good. Bought it for 70 cents (aluminum) on the pound (since I was working there) and replaced my cracked pump. My motor was good.

 

Forget the small engine magneto coil for a Hall sensor as they don't use them. The Transistor in them is switched on then off by the primary winding of the coil.

 

I am trying to repair a 1987 2 cycle engine golf cart ignition module. It appears to be a very simple circuit. Hall effect triggering the high volt transistor. But the several problems are that the main high voltage transistor failed turned black and one leg was melted where it meets the body of the transistor. In the past I think it was hooked to a non resistor coil.
During disassembly of the not serviceable part (ignition module) I broke / damaged the hall effect switch. I seen a post from many years back on the site that sourced the high voltage transistor but not the switch.
Long story short the module is about $200 new now or I have to go back to points. I would rather not do that.
Having very little knowledge on how to spec this type of part I tried the usual like Digi key and came up none available.

You are correct most modern lawn mowers use primary coil winding switching.
I am a Diesel Technology instructor and work with basic DC circuits a bunch, but this is a little out of my wheel house. I am willing to figure it out and learn it though.
thanks for your assistance It is a cool project for my kids and I.

Jay

 

Is this the circuit you are using? I have found 2SD1071 is a good darlington type Ignition transistor. HKZ 121 Hall sensors are salvageable from car ignition distributors from the wreckers (I get them free from scrap dealer) You could probably carefully cut the magnet away from the unit & use it.

 

I like the idea. I am a novice though this may take a bit of learning for me to incorporate. What make and model car does this come from?
The statement "cut the magnet away from he unit &use it". Would this be just for the trigger? Then build the high voltage transistor board externally to run the coil? Because that may be my best bet. It sure would be easier to make.

Yes that is the circuit.
I have a good start to the components but my knowledge base is hindering me when looking at the silicon hall effect. Not sure about things like "threshold of positive-going magnetic flux density" yikes I sure wish this meant something to me.
When researching the part using the desired absolute maximum ratings most come up short when it comes to supply voltage. The spec sheet for the TL170c shows input voltage at 7vdc. most I find come short with 5vdc again my knowledge thing. I suppose this might be minor but I am not sure.

thanks so much for the help

Jay

 

Here in Australia the Hall sensors are in Ford distributors & Mitsubishi distributors. These HKZ121 devises will run happily on voltages up to 24V. In the next few days I will try cutting one up & see if they can be used. Its nearly midnight here so ime of to bed.

 

This is what ive done with a HZ 121 Hall sensor so it can be used with a magnet on a flywheel. Its very similar to what you are looking for. This will handle upto 24V & 40Ma. Its glued to the aluminium bracket with 2 part Devcon glue. I have noticed using the above circuit, that when theres no magnet by the hall sensor the transistor is turned on. This may be why the original transistor had a melt down, possibly with ignition turned on & not running. Helps to know what country you are in for parts availability.

 

Thank you for your time and help. I was able source the parts for the old board. I will be using the parts debe suggested for a future project.
Again thank you for all your help.

Jay