automotive circuit / module design needed 2

[gerryfoster]

Hello all.

I'm new to this forum and would like to say hello!

I'm a custom shop owner and am prototyping a system and need some help.

ill describe to the best of my knowledge what im trying to do and what I'm looking for....

I am wanting to control a simple reversible DC motor roughly 1 amp draw.

I need to run this motor in both directions (reverse polarity)

here's where it gets over my head....

I need a current sensing setup to stop motor when it reaches its stop.

also i need a different type of input to control this motor, i want it to work exactly like a power antenna does? apply 12 volts to turn the motor and have it stop at it's limit, stay in that position until the 12 volts is removed, at that time turn the motor in the opposite direction until it again stops at it limit.

the use of this set up it to automatically control an electric exhaust cut out, which i have plans to control with another system which outputs the 12 volts on/off as mentioned.

i have a lot of experience in automotive electrical but not in the designing of circuity.

any help would be greatly helpful.

thanks Gerry

 

[Skogsgurra]

As several have already said; you have to do some experimenting to find out what works best.

LiteYear The lamp does NOT behave like a resistor. It has a low resistance when cold and resistance increases five to ten times when heated. That is why you get a decent torque from the motor and that is also why the motor doesn't burn out when stalled. Forget the linear calculation, it doesn't hold.

Also, a PTC increases resistance and "self-holds" so you need an alternate path to reverse the motor, as OperaHouse says. You do not need that with an incandescent lamp.

And, finally. The lamp allows a certain "holding current" so that there is always some torque left to keep things closed (or opened) at end-of-travel.

I think this circuit holds a world record in simplicity and functionality.

Gunnar Englund

http://www.gke.org

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Half full - Half empty? I don't mind. It's what in it that counts.

 

[gerryfoster]

http://www.grote.com/product.php?product_number=45822&x=0&y=0

thats the bulb currently in the circuit, its working great, but like i said im trying to get it all down in size to mount all the components in a poly enclosure of roughly 2"x1.5"x1.5". so a small snap in incandesant bulb would be optimal, got a dpdt 8 pin relay and snap mount relay socket to scale down the rest. right now im running 2 seperate relays.

ill track down a 100ma bulb and try it before i buy any quantity of the before mentioned ones.

thanks everyone, and like the last post states, this is so simple its not funny. love it.

Crappy Car Customs.......we make you CRAP custom!

 

[LiteYear]

LiteYear The lamp does NOT behave like a resistor.

Holy moly, you're quite right. The humble lamp really does provide non-linear resistance of 5-10 fold. That's awesome! Learn something every day.

So my post is mostly rubbish - only the fact that current will be capped at about 100mA is correct.