Transistor to switch circuit to ground

[neazoi]

hello I have designed this circuit http://neazoi.com/transistorizedcpu/punchcardreader.png. A pnp transistor switches on and connects the rest of the circuit to ground. the total circuit consumption is no more than 150-200mA.
The transistor I have used did not work. what am I doing wrong?

 

[goldsmith]

Re: Transistor to switch circuit to grond

Dear neazoi
Hi
What is the line that the emitter of RD16 connected to ? is that ground ?
Best Wishes
Goldsmith

 

[btbass]

Re: Transistor to switch circuit to grond

You need a series resistor connected to the base of the PNP.
A 1K should do it.
Otherwise you are shorting the emitter base junction to ground.

 

[mister_rf]

Re: Transistor to switch circuit to grond

Use a NPN transistor/ N channel MOSFET...

 

[neazoi]

Re: Transistor to switch circuit to grond

Dear neazoi
Hi
What is the line that the emitter of RD16 connected to ? is that ground ?
Best Wishes
Goldsmith

it is connected to a resistor which is tied to vcc

---------- Post added at 15:44 ---------- Previous post was at 15:41 ----------

can I use an npn without the driver transistor and a 1k base series resistor?what other smaller transistors can I use for 200mA switching?

 

[mister_rf]

Use for example a BD135/BD137/BD139 as in the previous diagram.

 

[neazoi]

Use for example a BD135/BD137/BD139 as in the previous diagram.

I wold like to avoid altering the driver configuration. would a 1k series resistor be enough? I think the BD transistors are overkill. could I use a 2n4124?