Guitar -> FET -> Minidisc

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Michael_Joly

Active member
Joined
Nov 11, 2004
Messages
42
Any suggestions for a simple FET impedance converter circuit to use between a guitar and minidisc?

I want to power the FET from the 3v-powered mic jack and use the minidisc as a guitar scratchpad.
 
Michael,

Try this, and change the 10k preset to a 2,2 or 4,7k preset and adjust the voltage on output to approx. 1,5 volt.

A 2,2k preset resistor= approx. 0,7 mA and 4,7k= 0,3mA current from your 3 volts source.

Because this low voltage circuit only can handle 1 volt with approx. 50 kohm load before clipping, and a guitar with high output pickups can give a lot of level over a hi-Z input, so maybe you must have a -10dB pad before the FET transistor input, (2,2 Mohm with a 18 pF capacitor in parallell and connected in series with the input) or turn down the volume knob on your guitar.

You can find the pad circuit here on my API 312 DI-modification
http://web.telia.com/~u31617586/#Bo%20Hansén's%20audio%20circuits%20design%20talk

Here is the orginal post that the circuit was use for from the beginning
http://www.groupdiy.com/index.php?topic=4187&postdays=0&postorder=asc&start=30

BTW, there are a lot of nice "rail to rail" low volt op-amps and buffer from Maxim that is made for small computer or telephone equipments with voltage feed from battery or USB interface.

--Bo

FET%20impedance%20converter.jpg
 
I see the changes, thanks.

I'm an old-fashioned, Low R, single coil guy myself - I don't think my pickups produce anywhere near 1V output. But but the volume control is a good attenuator especially since now it will be buffered.

I've wound my telecaster pickups by hand to lower than stock resistance readings - gives a brighter output and I don't mind the lower output level.

by the way Bo...

is it true that baked beans are as popular in Sweden as they are in New England?
 

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