Topics

A very simple question regarding Vref and an extra opamp I have laying around on a circuit I'm working on.
I have an opportunity to use this spare opamp and was thinking of using it for Vref.

At the moment, for the Vref, I am using 2x 22k resistors with a 47uf filtering capacitor. My question is, if I add the opamp, can the resistors value be the same or would I need to adjust their values?

I looked on the forum and couldn't find anything related to the BC459C, even though I'm pretty sure this has been debated to exhaustion.

I'm looking for an SMD version of the BC549C transistors. This is for a high gain fuzz (muff variant) and it's not easy to find smd versions of some trannys. The one that I can find is for the 2n5089...

I had already opened a similar post regarding the MPSA18 and I'm starting to realise that it's very hard to find some of these SMD versions of the transistors popularly used on so many fuzz units. 

I have been looking for an SMD package for the MPSA18 and I cannot find anything. Has anyone had any luck with finding this as an smd package?

Hi guys, I thought that I should ask the Peeps opinions on where to look in order to improve a little issue.
I have a design that, as many pedals, blends the clean signal with the Distorted signal. For this, I am using a Pan circuit with an inverting opamp stage. The Center of the Pot connects to VR (2x 10k resistors with a 39uf filtering cap.
The circuit works really well, except that, when completely on the clean side, there is bleeding from the distorted tone when the gain is up. I thought that the 39uf cap would be enough to filer everything, but it doesn't seem to do the trick.
I guess the question is, any idea where to look?

Hi guys, this is not a pedal enquiry, but it's actually something I'd like to lear about to end up using on a circuit.
I would like to drop the "Pot + Cap" tone system on a guitar and replace it with a switch(not sure which). The idea is to drop the potentiometer completely and instead have a 3 position switch(maybe on/on/on or on-off-on?) with two caps.
I'd like to have position 1: No cap( full sound); Position2: C1; Position 3: C2.

Is there a simple way of doing this using a 3 position spdt switch?
Any help would be appreciated.

I'm looking at finding the right parts to simulate a VTL5C3 optocoupler to be used in a compressor.
I wouldn't mind buying these if the prices weren't as high as they are at the moment, and I might need a few.

Has anyone roled out a DIY version of the VTL5C3 that stays close to the specs? If so, which LDR did you use and LED colour and type shoukld go with that specific LDR?

Thank you in advance, hopefully someone can help!!!

By the way, I have opened an Xvive and the LED is Green, diffused. The LDR when on reads 11k and off was more than 30M.

I finished my Rough Cut compressor build and I'm generally happy with it. It fired first time and it does what does well, even though, it would be great to improve on the Ratio of the compression. This leads me to the question, how would one go to change/determine and calculate the ratio of compression on this circuit or any other compressor by any means?

I have attached some pics of the finished build.

Hello everyone. Every time I'm in a pickle, I find it very useful to reach out here for other people's experiences and knowledge.
Having said this I would like to  know what options are out there for an smd JFET to be used as a buffer. It will be replacing an opamp and my aim is for it to be low current draw (what I'm using now is about 0.45 mA, so it should ideally be lower). As it will be a buffer, it should be able to take hotter signals as well.
I thought the mpf102 was the way to go, but it doesn't appear to exist in an smd format.
Hopefully someone can help with some useful information.

Hello guys.

I'm trying to find out what program do you guys use to make the PDF documents with the wiring diagrams?

I need to make a wiring diagram for a project I've made but I've never done the wiring diagram rather than drawing it by hand.
Is there any tutorial video on what program to use and how to use it? Is it possible to doing this using Gimp?

Any help would be appreciated.

So, here we go.
I have been on a quest to mix the two pickups on my bass. Both go through a preamp each and both have a 10k Volume pot at the end. I have designed a simple Summing amplifier to mix them in two ways.
The first time I used a Panning configuration and left the Volume pots out. Because I couldn't find the right type and value of pot(needed 10k center detent with long bush, and could only find a 50k), used the 50k and when in the center position there was too much volume drop. Tried with a 10k and it was great, but I just can't find the right type to use it as an onboard potentiomer. So I tried using 2 Volumes coming from the preamps and mixing them with this circuit. Now the effect is the opposite, it sounds considerably louder when both pickups are full.
Is there a way of using this 2 Volumes configuration where in the middle position the output will be simillar to when only one Volume is on Full?

Thank you in advance.
The Schematic is attached

Hi guys, I am making a couple of circuits and I'm trying to find out what people use to coat the back of the PCB for circuit protection?
These circuits are designed to be onboard and I'm worried that having the pads exposed could bring problems.
What would be a good and cheap method to coat the back of a pcb?
I have tried Araldite and Locktite Plastik. Both of them don't seem to be the way to go.

A simple question.
Impedance aside, on a typical situation where there's an output cap and a Volume pot in series with it, it forms a high pass filter. Well, does this filter change depending on where the pot sits, or is the series resistance in the audio path added to the resistance tied to ground?

Hi guys. I'm building a summing amplifier to mix a multi coil pickup. Since my bass already has another circuit preamp in it I was thinking of using something that performs as good as as a tl072 but with lower power consumption and same or less noise.
I would appreciate any suggestions.
Thank you

Hi, I have this board that is made already and uses one side of a TL062 as an LFO in a PT2399 chorus. Meanwhile the other opamp is left hanging. Does any one know how to properly terminate that opamp? I saw that wiring it as a voltage follower is the way to go by adding two resistors from the input to the Rail and 0V. Is that right? If that is right what value should it be for both resistors?
Sorry for the silly question.

Hi guys.
Trying to figure out a way of using a diode in series with the rail with the potential of losing the least voltage possible when powering from a 9v source.
The diode being used at the moment is a 1n4001 but that drops the voltage a bit and it would be good to try and keep the voltage as close to the source as possible when using it in series.
Hope someone will have some helpful information on this.

Thanks

Hi guys.
Got this wah wah pedal dated from 1979 that it's not working.
It uses two bc184C transistors, for reference, even though I have noticed that on similar circuits (fuzz wah pedal) found on the web, the second transistor is a bc167B.
The pedal has bypass working, when the effect is engaged there is some signal going through but at a very low volume and the pot is doing something but barely and very focused on the lower frequencies.
I have tested the switch and it's fine; wired an external pot to see if the pot was the problem, it is not. Checked if there was voltage going to the circuit from both battery and power supply. Replaced the caps and transistors to no effect.
Also inverted the second gain transistor to match the pinout of a bc167 but the result was exactly the same.

I am wondering if this could be an inductor problem? I don't have a lot of experience with Wah wahs, so, I don't know how to evaluate the inductor.

Hopefully someone could help with this one.

Hi guys. I have this circuit where the clipping section should have a pair of germanium diodes but instead it has a Red led and a yellow "diode"? I'm trying to identify what this diode is but with no luck.

I have built a couple of Deep Blue Delays and with the last one I have a weird working one. Everything works fine except that there is a winning (almost theremin like) hi-pitched noise always present on the Delay side. It becomes even more obvious once I start Rotating the Delay Pot as the noise moves with it.
The only significant changes I have made to the circuit was changing the input Gain and impedance from r2-180k / r3-390k configuration to 470k/ 470k respectively and used Tantalum capacitors for all 1uf caps on the Audio path.
I anyone could give me an hint on what to look for it would be appreciated.



Voltage on Pt2399

1- 4.93v   
2- 2.45v     
3-0v
4- 0v       
5- oscillates beetween 2.87 and 2.91v
6- 2.45v   
7- 1.92v     
8- 1.98
9- 1.5v     
10-2.45v     
11-2.45v
12- 1.42v
13-2.45v
14-3.85v
15-1.38v
16-2.45v

Hi guys, I have been away from the forum and I'm sure this debate has been covered before.
Anyway, after twicking with a Delay that I have built before, a Sea Urchin, I have noticed that with some pedals the Delay acts as a boost but with others it remains at unity gain. I was explained that this was due to the amplification being made on the inverted side of the opamp. I have also noticed that the pedals that make the Delay pedal boost are the ones that have a pot (Master Volume) on the output stage.
My question is:
If I want to leave the design as it is, would adding a simple jfet buffer at the input of the circuit control this boosting problem?

I haven't been to the forum for a while now.
Not sure if this is the best place to post, but I'll give it a try.

I need your help, bought this Guyatone Phaser second hand and it doesn't have the knobs. I would like to get these exact knobs but I have never seen anything like it. If anyone knows anything about these and where to get them it would be amazing.