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The diagram above shows the pin-out, schematic symbol and pad connection for a common anode LED.
The pin-out for the bi-color LED is as follows:
1
st
Colour Cathode
90 degree bend in the lead
Common Anode Middle lead
2
nd
Colour Cathode
45 degree bend in the lead
The pad for lead 1 on the circuit board is marked with a white box.
When connected correctly the LED will light red when power is applied and the circuit is in bypass mode. The LED will light green
when in effects mode.
When choosing a standard LED use center anode and non-white box
.
Using a standard LED, connect the anode to the middle pad and the cathode to the right pad to show the circuit in effects mode.
Build Notes and Mods
●
Socket both transistors to allow easy replacement or testing. BS170s should be used in Q1, but a variety of JFETs will work
in Q2. Be sure to verify the pin-out is the same. Try 2N5457 and MPF102 depending on the tone you want to achieve.
●
R10 is the CLR so adjust accordingly to the desired LED color and brightness.
●
Adjust TR1 so that the Drain of Q2 is at 4.5V.
You can do this by placing the “common” lead of your voltmeter to ground
and the “positive” lead of your voltmeter on the Drain of Q2 after it has been installed.
●
As with all diode clipping circuits, you can experiment with different diodes. BAT41s, 1N4148, Zeners, and many
Germanium types sounded good. 1N34A’s or BAT41’s sounded the best to my ears.
●
If you do choose to experiment, I recommend leaving the LED clipping in place (D4 and D5) and adjust D2 and D3 to taste.
●
When D2 and D3 are engaged,
there is a significant volume drop
, (it’s normal) but you may not find it optimized for your
setup. Experiment with R9 to compensate for volume. Lowering this value may help. Also doubling up the diodes or tying
an LED in series will bring the volume up. You can do this mod easily with one of our
DPDT Wiring Boards.
WIRING
