| Electronics > Beginners |
| Can I power this 6V preamp from 12V? |
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| Gyro:
Yes. The schematic doesn't say +6V and -6V. It has two lines, one saying + and the other saying -, with a '6V' near (below and above) the line. That was a big clue in an old hand drawn schematic. As I said previously, it's the way someone back then would have drawn it if it was going to be connected to a battery. The other clue is looking at the polarity of the electrolytic capacitors on the input and output. Both are oriented expecting the internal circuit nodes to be positive relative to the input and output signals. EDIT: The final clue is the absence of a marked 0V rail as an input and output reference. Without a 0V rail, there can't be separate +ve and -ve supplies. |
| Rigolon:
To Soldar and Gyro, I see, thank you for teaching me something new. I've misinterpreted the 6V on the lines as +6V and -6V. |
| soldar:
This preamp is very similar. It is taken from a book published in 1970 and mentions it uses silicon transistors which were relatively new at the time. It is not something I would build today except as a learning experience and to analyze it. Note that it is designed for 24 V but it can be redesigned for lower voltages by just changing the values of a few resistors. |
| ELS122:
I have figured out the preamp now there is a problem whit the coupling cap, my amp has a 50k pot on the input put volume and it whit the coupling cap from the circuit created a high pass filter. and if I put a 1uF electrolitic it starts conducting dc for some reason. also when I don't put another coupling cap at the end of the circuit it also conducts DC for some reason What could be the problem? NOTE: I know it's an overdrive circuit but it doubles as a preamp when I turn it down. |
| ELS122:
--- Quote from: ELS122 on October 22, 2019, 02:13:24 pm ---I have figured out the preamp now there is a problem whit the coupling cap, my amp has a 50k pot on the input put volume and it whit the coupling cap from the circuit created a high pass filter. and if I put a 1uF electrolitic it starts conducting dc for some reason. also when I don't put another coupling cap at the end of the circuit it also conducts DC for some reason What could be the problem? (Attachment Link) NOTE: I know it's an overdrive circuit but it doubles as a preamp when I turn it down. --- End quote --- when I put like a 47nF cap for DC coupling at the circuit it doesn't pass DC trough! |
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