TWS-434 Power Control Circuit

[haunsdoger]

HI,
I have a standard TWS-434 setup, Pin-4 Ant, Pin-3 5vdc/100mA, Pin-2 OPEN, and finally Pin-1 that is attached
to the collector of a 2n2222a NPN transistor. The Emitter is attached directly to ground. The base has a 470 ohm resistor.

Basically I am using the transistor to supply a ground to the TWS-434.

I want to control the TWS's ground with a positive voltage on the resistor.

When a positive is supplied to the resistor, the transistor will supply ground to the TWS - Pin 1.
When a ground is supplied to the resistor, the transistor will be open - thus removing the ground from TWS-Pin 1.


It does not work (transistor is always ON). Any suggestions? Should I use a PNP and control the supply voltage to
the TWS?

Thanks in advance for any suggestions!
George

 

[BradtheRad]

The arrangement you describe ought to work as long as the 2N2222's specs were not exceeded.

To make sure it is still good, you will need to test it out of circuit.

A PNP will not necessarily work better at the low side.
Its emitter (more positive terminal) needs to see a definite path to the positive supply.

You might prefer to use a PNP to go between the unit and positive supply.

 

[haunsdoger]

The arrangement you describe ought to work as long as the 2N2222's specs were not exceeded.

To make sure it is still good, you will need to test it out of circuit.

A PNP will not necessarily work better at the low side.
Its emitter (more positive terminal) needs to see a definite path to the positive supply.

You might prefer to use a PNP to go between the unit and positive supply.

Thanks for the reply! - I agree. And yes to the PNP placement.

 

[RK_ELECTRONICSWORLD]

Thanks for the reply! - I agree. And yes to the PNP placement.

I have also used npn transistor (BC547) to control the RWS-434 GND in same configuration as u have describe and it works fine but i have used a 10k resistor with pull-up on transistor base.