Help with project

[Tim @ P.I.S.]

Hi, first post.

I am trying to build a simple project but i am not the smartest with eletronics.

If anyone can help it would be greatly appreciated.

Project: I need to apply anywhere from 100-140 volts DC to a device. The catch is i need to be able to adjust the "pulsewidth" i am apply it from 2 millsec to as much as 7 millsec, and be able to automatically have it count off 500 or 1000 activations(on-off-on-off and so on).

Not quite sure where to start or what all componets i will need. I have no circuits drawn up for this yet either. So far all i have is this idea in my head.
Thanks

 

[RODALCO]

Firstly you are a bit vague with what you want to built.

Secondly if you are not that experienced don't you think that 140 Volts DC is safe to experiment with ?

I would first suggest, try to build something easier with lower and safer voltages instead of going direct to higher voltages which could give you a nasty shock or possibly kill you in the process.

 

[Tim @ P.I.S.]

Firstly you are a bit vague with what you want to built.

Secondly if you are not that experienced don't you think that 140 Volts DC is safe to experiment with ?

I would first suggest, try to build something easier with lower and safer voltages instead of going direct to higher voltages which could give you a nasty shock or possibly kill you in the process.

Thanks for you warning. I do work with electricity every day. Up to 480 VAC daily so I do take caution. I thought this would be a little hard to explain, sorry.

Maybe this will help. I am trying to build an fuel injector test stand.

This injector runs off a trigger of 110-140vdc to activate. It then operates off of a pulsewidth to keep it "on" to injector fuel. This is the on-off activation i need. But i also need it to count off either 500 or 1000 "fires" or activations so i can measure the amount of fuel that has been used.

Maybe this better explains what i am in need of.

 

[evandude]

do you already have a DC source to get this 110-140vdc from, or do you need to build that too?

do you already have a method of manually switching the injectors?

I would expect the switching part to be the biggest headache. I've never worked with such high DC voltages and don't know what kind of current you'd be needing either, so I can't really recommend anything in particular, I would expect it would be doable with some form of power transistor.

If you can get the switching to the point where all you have to do is apply a logic-level signal to your switching circuit with the right pulse width, then the rest should be a piece of cake with a microcontroller; generating a pulse between 3-7ms and keeping track of the number of pulses would be very simple.

 

[Tim @ P.I.S.]

do you already have a DC source to get this 110-140vdc from, or do you need to build that too?
This is part of the problem too. I am not set up with this yet.

do you already have a method of manually switching the injectors?
No, i really have nothing as of yet except the idea.

If you can get the switching to the point where all you have to do is apply a logic-level signal to your switching circuit with the right pulse width, then the rest should be a piece of cake with a microcontroller; generating a pulse between 3-7ms and keeping track of the number of pulses would be very simple.
This is what i need more info on. Do you have any links to something of this mannor for me to look at?

Thanks again guys.