Modifying this simple transistor circuit so that it can be triggered by a 5V proc signal

Thread Starter

chad2057

Joined Sep 20, 2020
15
Hi,
Learning here.
Would need some help modifying this circuit.
In the circuit below, V2 controls when Q6 conducts:
When V2 is set to a 5V (negative) voltage, you see 12V at Out.
When the output of V2 is changed to 0V, Out is close to 0V.

I would like to change it, so that it can be controlled by a voltage from a processor like an Arduino board:
5V turns Q6 on.
0V turns Q6 off.
Any ideas?

q1.png
 

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sghioto

Joined Dec 31, 2017
5,390
The output from an Arduino is not a negative 5 volts.
Some people misinterpret this as a minus voltage moving from +5 volts to zero.
Obviously if V1 is zero then the output is always zero.
 

ericgibbs

Joined Jan 29, 2010
18,849
hi chad.
You asked for this
I would like to change it, so that it can be controlled by a voltage from a processor like an Arduino board:
5V turns Q6 on.
0V turns Q6 off.


That is exactly how my circuit functions in post #7.

How is it wrong???

E
 

Thread Starter

chad2057

Joined Sep 20, 2020
15
Thanks for the responses. To clarify, this is the truth table for the desired circuit:

Base of Q6 Out
-----------------------
______0V __________ 0V
______5V _________12V

I hope it makes sense.
 

MrChips

Joined Oct 2, 2009
30,810
You can do it with a two-stage common emitter BJT configuration.
Or you can use an IC such as SN7407 hex buffer or dual peripheral driver SN75451, etc. Note that these have open collector outputs and require a pull-up resistor to +12V.
 
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