how to convert .5 volts to 5 volts
how to convert .5 volts to 5 volts
(OP)
I have screwed up two different servo motor controllers somehow. The output called PFIN or position finished is usually 24 volts or nothing, 24 being ON, and nothing being motor in motion. These controllers are a lot of bucks and since now the damaged outputs(open collector pnp) are putting out 0v for ON and .5v for OFF, maybe I can salvage these two controllers by converting the small voltages to 5 volt logic. I tried using a simple switching transistor(2222) to turn on 5 volts but it wouldnt do it. Any ideas on how to do this?





RE: how to convert .5 volts to 5 volts
If you know you have a blown open collector transistor just fix it... You don't even need the same kind if you can't read the part. Just something close.
If you must use the crummy output then you need to use an op-amp as a comparator to compare the drives output to 0.25V. If over that: one state, under that the other..
Google comparitors ..lots of pages.
RE: how to convert .5 volts to 5 volts
If this open-collector transistor output was accidentally connected to the 24V rail directly, that would explain the fried output. Likewise if the load was 10R or similar.
Notice that now the output is inverted. Are you sure you have a pull-up on it? You should apply nothing to teh base to get no collector current to give 24V. If you apply base current you get 0.7V on the base. If there is no pullup resistor then the base-collector junction may allow current to flow giving the signal you are seeing.
RE: how to convert .5 volts to 5 volts
RE: how to convert .5 volts to 5 volts
The manual does not mention using a pullup, and they actually use only a 2k resistor and led for their demonstration units. I was using a 4.7k into a photocoupler to create some 5v logic, still unsure how I smoked it, unless without seeing it I dragged 24 across a trace.
Thanks for the suggestions.
RE: how to convert .5 volts to 5 volts
RE: how to convert .5 volts to 5 volts
Sorry but that's the way it is. The 0.5 volt could only be temporary and soon the damage could get worst.