[SOLVED] Help 3.3V logic controlled switch that has negative output voltages

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ckaven

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Hello,

I have an elementary electronics question. I have attached a circuit i need help solving. V1=5V and V2= -30V. what i need is to be able to control the switch with 3.3V logic. Vcntrl(0V)=off ---Vout=-30V; Vcntrl(3.3V)=on ---Vout= -27V. I dont care what type of device is used as the switch (BJT, FET, etc). The resistor values in the circuit give me the correct Vout if I can just get the switch to behave. Please help!!! Havent done transistor biasing in years and regretting the loss of the skill. If possible please post supporting equations for the solution. This isnt the only circuit i have to design like this. All have different negative V2 values


thanks

Kyle
 

Re: Help 3.3V logic controlled switch that has negative output volatges

I think you can use the following circuit, any NPN and PNP would do the job



Alex
 
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