The Beatles Pedal

CheapPedalCollector · Post by **CheapPedalCollector** » 13 Feb 2023, 06:32

What is this pedal trying to achieve?

deltafred · Post by **deltafred** » 13 Feb 2023, 09:28

CheapPedalCollector wrote: ↑13 Feb 2023, 06:32 What is this pedal trying to achieve?

Sales!

grrrunge · Post by **grrrunge** » 13 Feb 2023, 21:43

deltafred wrote: ↑13 Feb 2023, 09:28
CheapPedalCollector wrote: ↑13 Feb 2023, 06:32 What is this pedal trying to achieve?
Sales!

Exactly. And maximum return of minimal investment

CheapPedalCollector · Post by **CheapPedalCollector** » 13 Feb 2023, 22:30

blackcorvo · Post by **blackcorvo** » 02 Mar 2023, 04:33

Are you sure it's not a circuit inspired by the tube sound overdrive?
https://nexp.pt/arsenio.html
Could explain the two transistors.

deltafred · Post by **deltafred** » 03 Mar 2023, 11:53

blackcorvo wrote: ↑02 Mar 2023, 04:33 Are you sure it's not a circuit inspired by the tube sound overdrive?
https://nexp.pt/arsenio.html
Could explain the two transistors.

That would make a lot more sense as it would give more of the pushed valve (tube) amp sound.

pilau · Post by **pilau** » 06 Mar 2023, 18:38

Thank you all for pitching in! I've been a bit busy with work etc. but I'm back. Following up on everything.

CheapPedalCollector wrote: ↑13 Feb 2023, 06:32 What is this pedal trying to achieve?

Trying to recreate the sound of Vox UL730 and Vox Conqueror, or in other words, sound like the Beatles

blackcorvo wrote: ↑02 Mar 2023, 04:33 Are you sure it's not a circuit inspired by the tube sound overdrive?
https://nexp.pt/arsenio.html
Could explain the two transistors.

That looks quite suspiciously similar! Will definitely use it as a reference. Thanks!
What are VM1, VM2, VG1 and V19 in this circuit?

What is the function of this 100ohm resistor? (marked in orange) Link to picture of full PCB for context

andy-h-h · Post by **andy-h-h** » 06 Mar 2023, 20:20

Check the schematic that grrunge posted on the previous page. The 100ohm resistor forms part of the standard power filtering and protection system, along with the 1N400X diode, ceramic (100n?) & electrolytic capacitor (probably 100u at a guess)

pilau · Post by **pilau** » 06 Mar 2023, 22:21

andy-h-h wrote: ↑06 Mar 2023, 20:20 Check the schematic that grrunge posted on the previous page. The 100ohm resistor forms part of the standard power filtering and protection system, along with the 1N400X diode, ceramic (100n?) & electrolytic capacitor (probably 100u at a guess)

Thank you very much, but can you explain exactly how it functions as part of the power filtering and protection system? What is its purpose?

grrrunge · Post by **grrrunge** » 07 Mar 2023, 04:47

It's a passive first-order low-pass filter with a corner frequency of 1/(2*pi*R*C)
Look up passive RC filters for more info

pilau · Post by **pilau** » 07 Mar 2023, 11:57

grrrunge wrote: ↑07 Mar 2023, 04:47 It's a passive first-order low-pass filter with a corner frequency of 1/(2*pi*R*C)
Look up passive RC filters for more info

Thanks grrrunge, I didn't realize it was just an RC filter. Thought there was more to it!

blackcorvo wrote: ↑02 Mar 2023, 04:33 Are you sure it's not a circuit inspired by the tube sound overdrive?
https://nexp.pt/arsenio.html
Could explain the two transistors.

What are VM1, VM2, VG1 and V19 in this circuit?

FiveseveN · Post by **FiveseveN** » 07 Mar 2023, 14:04

Voltage Meter 1 and 2, Voltage Generator 1 and Voltage (Generator) 1 (the sequel): 9 volts. They are required to compute the transient simulation in the insert. Look for TINA-TI or SPICE in general to learn about circuit simulation.

pilau · Post by **pilau** » 08 Mar 2023, 09:22

FiveseveN wrote: ↑07 Mar 2023, 14:04 Voltage Meter 1 and 2, Voltage Generator 1 and Voltage (Generator) 1 (the sequel): 9 volts. They are required to compute the transient simulation in the insert. Look for TINA-TI or SPICE in general to learn about circuit simulation.

Thanks, that helps! I see now that these volt meters are used to plot the scope to the right of the circuit. I definitely want to try simulating this circuit with LiveSpice.

grrrunge wrote: ↑05 Feb 2023, 20:57 IMG_20230205_214421.jpg

This is probably a good starting point for experimentation.

So I started working out your suggestion (thanks again for taking the time to make it). I'm focusing first on the reverse polarity protection and power supply decoupling:

I was trying to compare that circuit with the rest of the information and make out what the traces could look like on the back of the PCB. If I got you right, grrrunge, this is what you're suggesting? (The dashed line avoids obscuring the image. Excuse the crudeness, I made it on my phone)