D desmond New Member Apr 12, 2004 #1 harlow there, if i have a voltage range from 0.6 volts to 1.4 volts, can i use transistor to switch on a typical LED which has the forward voltage at round 2 volts? If cannot, how can i do that? Thanks in advance :wink: Desmond.
harlow there, if i have a voltage range from 0.6 volts to 1.4 volts, can i use transistor to switch on a typical LED which has the forward voltage at round 2 volts? If cannot, how can i do that? Thanks in advance :wink: Desmond.
F fat-tony Member Apr 12, 2004 #2 Are you saying you have an input voltage of 0.6V to 1.4V? Is there a supply that you can use too?
D desmond New Member Apr 12, 2004 #3 the supply i used actually is 5 volt, but due to a circuit there, the output i have is 0.6volt to 1.4volt (the range) ... then i would like to prove that the voltage there is not 0 so i am thinking to use LED as the indicator. so do you think 0.6volt (we take the minimum) can switch on a LED by using transistor? maybe bjt or mosfet? or what should i do? Thanks. Desmond
the supply i used actually is 5 volt, but due to a circuit there, the output i have is 0.6volt to 1.4volt (the range) ... then i would like to prove that the voltage there is not 0 so i am thinking to use LED as the indicator. so do you think 0.6volt (we take the minimum) can switch on a LED by using transistor? maybe bjt or mosfet? or what should i do? Thanks. Desmond
F fat-tony Member Apr 12, 2004 #4 The problem is that 0.6V is just a little lower than the Vbe for most BJTs. I'll think about it a bit more and get back to you .
The problem is that 0.6V is just a little lower than the Vbe for most BJTs. I'll think about it a bit more and get back to you .
F fat-tony Member Apr 12, 2004 #5 If you're not adverse to using an op-amp, it would get a lot easier
D desmond New Member Apr 13, 2004 #6 yeah .. i am thinking the same way too i will try it out with LM751 first lar .. thanks man ~ :wink:
John Sorensen New Member Apr 13, 2004 #7 The LM331 is a component I have enjoyed lately. Maybe it would be handy for you. It comes in a convenient SOT-5 package. j.
The LM331 is a component I have enjoyed lately. Maybe it would be handy for you. It comes in a convenient SOT-5 package. j.