I have found a cool distortion pedal schematic online that I am going to build in class. It is an MXR distortion pedal from the 1970's. What's good about this pedal is first off, we have all the parts needed to build this at school in the locker. The second interesting thing about this pedal is it has a dual power source option, from either a battery or a plug in right from the wall. This is possible by the two power inputs being connected to different parts on the quarter inch jack. The AC power supply is connected to the battery being connected and activated through the ring of the jack, and the AC power supply being connected and activated through the tip of the jack. This way, you can have two options to powering up the pedal.
http://distortionpedals.org/wp-content/uploads/2012/10/mxr-distortion.gif
Joe
Very cool! I definitely think we should build this as well.
ReplyDeleteYou're close, but not quite there. Have another look at the schematic.
ReplyDeleteAnd, remember the other bit we talked about as a potentially cool aspect to experiment with: using the 741's offset nulls to asymmetrically clip a waveform.
ReplyDelete"When using the LM741, one of the inputs will have a bias (usually non-inverting input), which means the output can never be 0 V. If a 0 V output is needed, you need to offset the bias. To do this, you can connect both inputs to two 1K resistors in parallel, or both inputs to either side of a 10K potentiometer. This will allow an output of 0 V from the opamp." -OR we could use the pot to tweak the waveform...
This might help you understand the power switching:
ReplyDeletehttp://www.diystompboxes.com/smfforum/index.php?topic=88509.0;prev_next=prev
or this:
http://www.diystompboxes.com/wiki/index.php?title=Frequently_Asked_Questions_%28DIY_FAQ%29#JACKS