npn transistor AO

[enri79]

Hello all,

I'm using compactRIO 9004 and I'm trying to setup a simple DC motor control using a NPN transistor (BC547B).

The setup is the following:

B connected to AO (0-10V)

E to ground (of AO module and of 1.5V battery)

C to one pole of the DC motor

The other pole of the DC motor is connected to the +1.5V battery

A diode is placed between E and C

The AO appears to work correctly (voltage can be measured with a multimeter or read from an AI) however the transistor does not react and the motor does not move.

The VI has been programmed in FPGA mode and it's very basic (just one AO and one AI for testing purpose).

I've tried adding a 10K resistor between AO and B but that did not help either.

In case anyone managed to setup something similar I'd be grateful for any suggestion.

NOTE exactly the same setup works no problem with ARDUINO (B driven from AO 0-5V).

Thanks

[Maxmuc]

Hi!

Did you try to use a different transistor?

And could you add a circuit diagram?

Max

[enri791]

Hi Max, thanks for the reply.

I solved the problem yesterday using a voltage buffer (op-amp LM358) between AO and the base of the transistor.

The transistor can now be switched on and off, however the voltage-speed characteristic is not very linear.

I wrongly expected the AO to be able to drive a low power transistor straight away but maybe it's not meant for such a use.

Thanks anyway!