not directly audio, need help for my router !

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flaheu

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Feb 15, 2005
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Land of the chicon south - yep
ok, as I said few weeks ago, I had the chance to get a big old router in good condition.
This router has tree 5 phases step motor with their respective amplfier, but the controller which send pulses and signals to motor's amplifier is fried.
I've bought a new controller from gecko drive which work with a pc.

My problem is that the former controller's output used to send "open collector against ground" type signals, but unfortunately the new controller just gives standard 0-5V pulses ans signals.

Anyone has an idea to convert 0-5V signals to "open collector" signals.

Sorry if I'm a bit confusing, I'm really not familiar whith this kind of stuff.

Thanks
 
Need more infomation about what the router input is like.

Open collector drivers are what is written a transistor with the collector open. The collector is then connected to a load a resistor lamp relay etc. A 5v high in will turn the transistor on VIA the load it is driving

maybe a chip like this after the gecko

http://focus.ti.com/docs/prod/folders/print/sn5407.html
 
[quote author="flaheu"]BUMP :oops:

Anyone to guide me ?[/quote]

Jakob's answer is good.

To help explain: a TTL output is what's called a "totem-pole" (push-pull) output. The output has two NPN transistors, one with its collector connected to VCC and its emitter connected to the output, and the other with its collector connected to the output and its emitter grounded (basically). A logic high output happens with the upper transistor turns on and pulls the output up to VCC and a logic low output happens when the lower transistor turns on and the output is pulled low.

An open collector "driver" is just that. There's no upper transistor, and the output is literally the collector of the lower transistor. A logic low output happens with the transistor is turned on, pulling the output to ground. But when the transistor is off? Nothing. An external pull-up resistor is required, so when the transistor is turned off, the resistor pulls the output up to VCC.

A possible reason that your original controller used open-collector drivers is that whatever it controlled is connected to a supply greater than TTL's 5V. Your drawing shows a 15V rail so I suspect that's what the OC driver is switching.

You could use a discrete NPN on your TTL output to make an OC driver. Put a resistor in series between the TTL output and the transistor base to provide enough base current to turn on the transistor. Emitter goes to ground.

Good luck,
-a
 
Thanks Guys,

Which model of ULN200X should I take ?

On the specification sheet of the former controller all output where rated 20mA, apparently under 24V.

Jakob said the ULN2003 which has a 2k7 at the Transistor base, is that the correct one ?

I'm sorry if my questions are dumb...

Thanks again :thumb:
 

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