In my case, adding a potentiometer between motor and power, this quick method to control motor speed didn't work at all so I used PWM using 555 timer to control motor speed. Some benefits of using 555 timer are I can add CV and gate inputs. Probably the quick method would work with other cassette player.
SCHEMATIC
UPDATE on 20220913:
With 1uF, the motor rotates non-linearly. So you can stick with 200nF for linear rotation.
UPDATE on 20220810:
For better speed control, I replaced 200nF with 1uF and 'Linear' 100k potentiometer with 'Log' 100k one. The schematic above has been updated.
Instead of using pin4 of 555, I switched to pin2 for gate input. Both works fine but conversely. It's up to you. But keep that in mind when using pin4, switch pin of 3.5mm jacks should connect to Vcc and disconnect Vcc from pin4.
STRIPBOARD LAYOUT
UPDATE on 20220913:
With 1uF, the motor rotates non-linearly. So you can stick with 200nF for linear rotation.
UPDATE on 20220810:
For better speed control, I replaced 200nF with 1uF and 'Linear' 100k potentiometer with 'Log' 100k one. The stripboard layout above has been updated.
This cassette player has a line output which jack is stereo one but actually left and right signal summed to mono in the circuit. One thing bothering me is its output gets mute when I plug mono cable into it because 'ring' pin of stereo jack was in contact with ground pin of mono plug. If you use stereo split cable, nothing wrong with it, however if you just want a mono signal like me, unsolder the stereo jack and cut the two legs corresponding ring side.
And I encountered some issue while using CV with my eurorack modules. Those seemed like ground issue. After some investigating, I found out its line out jack's ground was floating. So you need to connect the ground pin of line out jack to other ground point.
THOMAS HENRY CMOS ADSR Original Schematics: LINK1 , LINK2 STRIPBOARD LAYOUT -All diodes are 1N4148 -555 timer chip should be CMOS one like...
The layout is actual size so you can use it as a drilling template.
I used 12mm thick merbau edge glued panel and M3(13mm long)bolts. And I tapped the holes with a M3(0.5mm pitch) tapping bit. If you are using different size of wood and bolts, please be careful the tip of M3 bolts don't touch the pcb.
As a finish, I applied boiled linseed oil which is good to darken the wood, but its smell is not pleasant and lasts so long.
This module is MFOS Echofxxx. Original schematic and BOM: MFOS STRIPBOARD LAYOUT -D1 & D2 = 1N5231 -D3 & D4 = 1N914 or 1N4148 -10...
The original circuit was good enough to use, however I wanted comfortably aligned 10Vpp outputs. So I added a simple opamp circuit to get the outputs 10Vpp and aligned from 0v. You probably wonder why I used fixed resistors instead of trimmers to control output voltage. Because I decided to add the opamp circuit after having finished 555 timer circuit, so there were not much room. I would have used trimmers over the resistors to get more precise result if I build it from scratch.
STRIPBOARD LAYOUT
All the trimmers are multi-turn trimmers.
FACEPLATE LAYOUT
The layout is actual size so you can use it as a drilling template.
It's a usb lamp using 555 timer. STRIPBOARD LAYOUT CABLE PINOUT The color codes might be different from above. In the case, you woul...
This module is an attenuator and an inverter at the same time and also a mixer with an additional input.
It works as an attenuator when the potentiometer is from center to right (fully clockwise) and when you rotate the potentiometer counter clockwise from center, it starts inverting the signal.
STRIPBOARD LAYOUT
I used +5v from PSU, so the offset function might be unstable.
If your PSU doesn't have +5v or you are worried about it, you would build it with LM4040. In the near future, I'd also build another one with LM4040 and compare both and see the difference.
And the potentiometers I used are center-detented, which is so convenient to know where 0v is.
As always I soldered 100nF decoupling capacitors underneath the boards so you can't see them on the stripboard layout. So please don't forget soldering decoupling capacitors when you build this module.
FACEPLATE LAYOUT
The dimension is 40mm x 129mm.
This layout is actual size so you can use it as a drilling template.
Code & Schematic: LINK STRIPBOARD LAYOUT LAYOUT UPDATED on Nov.19.2022 -corrected 10k resistor to a push button, which was wrongly conn...
Original schematic and more information: LINK1, LINK2
STRIPBOARD LAYOUT
I built it as 12v eurorack version, however somehow triangle and saw outputs exceeded 10v and sine out didn't reach 10v. So I replaced some resistors to get 10Vpp.
All the transistors are 2N3904, however the two TRs on the board where LT1013 is placed should be matched.
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