- on Audio/Video/Photography
- Published in issue 7/2010 on page 87
(Summer Circuits 2010 article)
Most guitar pedals obtain a high input impedance simply by using a large resistor at the input of the first opamp, but this generates a good deal of noise due to the input bias current. The Glass Blower avoids this by using a smaller resistance (R2) which is bootstrapped by C2 to an effective value of tens of megohms.
September 22, 2010.
On the component layout of the PCB designed by the author (free download # 100165-11.zip), transistor Q2 (2N3906) should be turned 180 degrees.