DIY Compressor Kit Wiring Diagram professional Analog D.I.Y Guitar Pedal Effect Landtone Ttone Amazon [documentation]

[asbestosaurus]

just out of sheer curiosity i traced and drew up a schem from pictures of the PCB a while back. didn't figure it would be very relevant... until now.

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1202111369-518652627.jpg

lt comp.png

landtone compressor schem.PNG

didn't bother drawing the switching layout but its not too hard to figure out. effect input is grounded through the 47 ohm and swaps a ground connection with the status LED on bypass.

[FiveseveN]

Wow, that ground pour has me all kinds of confused.
The battery is switched in by the input jack like 90% of commercial pedals, maybe they missed that?

[Ben N]

Well, it definitely isn't an Orange Squeezer. It's an optical compressor, while the OS is an FET compressor.

[Blue Jinn]

I just bought one of these and it should arrive in January. It looks like a clone of the DoD 280. The picture has a photocell and LED, with no shielding. My plan is to use a proper vactrol. Thanks to OP for tracing out the schematic.

[Blue Jinn]

Put this together. A few observations:

1. It's a DoD 280A clone. The schematic above is almost the same as the ones found at GGG and Tonepad.

2. It comes with what appears to be a random LED and a LDR with no shrink tubing. I had a VTL5C2 on hand for another unfinished project so used that instead. The GGG has a variant with a NSL-32 which are cheaper.

3. Soldering to the small tabs on the pots, and soldering two wires to "PWC" is a little challenging. I wound up putting a blob of solder on the pot tabs and "spot welding" the wires to them, and then using some shrink tubing to keep it connected. Same with PWC, used leftover lead, twisted the two wires, and hooked the leftover lead, soldered, and held that with shrink tubing, So shrink tubing is necessary IMHO.

4. I've never used a "real" DoD 280 so can't compare. But based on reviews, this acts the same. With guitar and higher levels of compression it does crap out and drop the signal initially quite a bit. But with lower levels it is pretty subtle and musical. I'm using it on a Rhodes with inconsistent action, right before a phaser and it's pretty good. The GGG and Tonepad schematics call for a LF358 OpAmp. This comes with a 4558. I swapped in a 1458 for the heck of it, and it still sounds OK. I also put in a pin header for the resister in parallel with the LDR. The Tonepad schematic has it a 1M, the GGG at 3M and there are reviews about that as well.

5. It's an easy build. The VTL5C2 is about US$13 plus shipping from SmallBear. The NSL-32, Macron, and NOS CLM8000s about US$5-7. But overall cost with the "upgrades" is still a bargain.

[medvital]

Hi everyone, I'm new and this is my first project. I have assembled the pedal but it doesn't work. Tried to check the voltage with a multimeter and got the following results:
I connect the DC Jack to the power supply and all along the red line there is 9v. I also connected the + and - on the battery board directly, since I don't have a battery yet. There is 0v on the blue line and also on the rest of the board. Is this the way it should be? Where should I dig further?

[Intripped]

[...] I also connected the + and - on the battery board directly, since I don't have a battery yet.

if you mean that you've put a jumper between the + and - on the board, well, remove that jumper!

then, which is the polarity of the power supply that you're using? i suspect that it isn't center negative but center positive, since you've measured +9V where there should have been 0V. it must be CENTER NEGATIVE

image-11.webp

PWC from the supply-jack should be connected to GND (there are many GND pads on the board, i would choose the one in the middle)

ground-symbol.png

ignore the "wire" they say to put across the 47n (473) capacitors
please post a good pic of the instructions, i will draw on it the correct wiring.

[mictester]

Well, it definitely isn't an Orange Squeezer. It's an optical compressor, while the OS is an FET compressor.

It's (more or less) a copy of the old DOD280 compressor.

It's a really simple circuit:

The left op-amp carries the guitar signal, and its gain is determined by the 1MΩ feedback resistor, the compression control, and the LDR (Light Dependant Resistor). The op-amp on the right is just used as an invertor to turn the signal upside-down. The two transistors are driven by the op-amp outputs, and when they begin to conduct, the LED will light up - the louder the input, the brighter the LED. That LED is in close proximity to the LDR. When light falls on the LDR its resistance reduces, increasing the amount of negative feedback around the left op-amp, and so reducing its gain. This gives you compression - the louder the sound, the lower the output, and as the note fades, the gain rises, extending ("sustaining") it. The circuit tries to keep the level of the guitar signal on the output as constant as it can manage.

It's not designed to be a hi-fi compressor, but it is a cost-effective way of getting clean sustain.

[Intripped]

Landtone compressor wiring diagram.JPG

i've made a wiring diagram.

EDIT: i've added some instructions

here is an example of a PCB with the missing connection (and a jumper added)

PCB with missing trace.JPG

[medvital]

Landtone compressor wiring diagram.JPG

i've made a wiring diagram.

EDIT: i've added some instructions

here is an example of a PCB with the missing connection (and a jumper added)

PCB with missing trace.JPG

OMG, sorry i've just seen your reply.
You are right, my DC was center positive. I bought an another one and recompile with your instruction and now it's working!

In addition, new schemes are changed in compare with olds and they no need jumper anymore across the 47n (473) capacitors

SchemeDiff.png

Now my circuit, although it sends a signal when bypassed, the signal when the pedal is on is too weak at all potentiometer positions, looking for the problem

My board, assembled using new Intreipped's wiring diagram:

photo_2025-04-03_02-26-06.jpg

photo_2025-04-03_02-26-25.jpg

[Intripped]

cut off that white wire between the two 47n capacitors

[medvital]

I did it, just have attached an old picture accidently

[x-tn]

Now my circuit, although it sends a signal when bypassed, the signal when the pedal is on is too weak at all potentiometer positions, looking for the problem

Do you test the circuit in a box? If you test it in daylight, the LDR sees constant light, so it constantly compresses your signal.

[medvital]

Now my circuit, although it sends a signal when bypassed, the signal when the pedal is on is too weak at all potentiometer positions, looking for the problem

Do you test the circuit in a box? If you test it in daylight, the LDR sees constant light, so it constantly compresses your signal.

I tested the circuit covering LDR with some cup or whatever, same result
I'll test all components again later this evening and post here if something went wrong