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Design a on off switch to turn on a LED

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jcheng03

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I have a quiz question. I have p-channel and n-channel bipolar transistor, resistor, a LED, 2 tact push buttons, power source.
Need to design a circuit when i press the On button once and release, the LED will turn on. When I press the Off button once and release the LED will turn off?
Any idea? Please help?
 

jcheng03 said:
I have a quiz question. I have p-channel and n-channel bipolar transistor, resistor, a LED, 2 tact push buttons, power source.
Need to design a circuit when i press the On button once and release, the LED will turn on. When I press the Off button once and release the LED will turn off?
Any idea? Please help?
Click to expand...

You should try this simple basic circuit, it use an pnp and a pnp bipolar transistor.
Bipolar transistors don't have channel!
 

    J

    jcheng03

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Thanks for your help. However, it looks like this will work if the keys are permenantly switch on/off. if we use the push button tact STSP momentary switch. It fails to work? Please advise or any other comments??
 

jcheng03 said:
Thanks for your help. However, it looks like this will work if the keys are permenantly switch on/off. if we use the push button tact STSP momentary switch. It fails to work? Please advise or any other comments??
Click to expand...

Sorry for the symbol that I used for S1 and S2.
S1 and S2 are buttons not switches.

stefano
 

The quiz question is to use the tact push button STSP, when press once and release, so only one pulse generated. How to design this? like a state machine???
Flip flip like?? any idea???
 

Circuit suggested by Stefano does exactly that: one short positive pulse on the START and the LED is ON, one short pulse on the STOP and the LED goes OFF ..

Regards,
IanP
 

After i carefully review the circult, I understand now. Thanks again. I like this site very much....
 

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