Do you have a one-knob TL071 boost?

[jdduffield]

I need a simple and clear one knob boost for a mandolin. I have a stash of TL071 op amps and wondering if you have a PCB that uses that component in a simple, one-knob boost.

 

[Cybercow]

Check this out . . . . . https://www.pedalpcb.com/product/pcb633/
The trimpot can be replaced with an external pot.

 

[BuddytheReow]

Good news is you can breadboard something using a simple inverting opamp configuration. I will refer you to the first half of the Mini Muffin schematic plus the power supply section. The pinout for the opamp below is for a dual, not a single such as the TL071. Replace R4 with a output coupling capacitor and that's your output. You can replace R3 with a 100k resistor plus a 250k (just a guess) pot using pins 1 and 2 to be a variable resistor.

This can easily be built on stripboard. If you need help with a layout just let me know and I'll see if I can whip something up.

 

[jcpst]

Another tl071 boost

FDIC Boost - PedalPCB.com

Compare to Fulltone 2B

www.pedalpcb.com

Edit: whoops, two knobs there.

 

[spi]

a microamp comes to mind

MXR Micro Amp

Collection of vero (stripboard) & tagboard layouts for 100s of popular guitar effects, with over 1000 verified designs. DIY your own boutique effects!

tagboardeffects.blogspot.com

 

[spi]

Also, the google query

site:pedalpcb.com filetype:pdf tl071

will bring up some of the build docs that have tl071 in them. Looks like one of the top hits (Celsius) is a 1-knob w/ a tl071, as is the Triangulum (both of these also have a chargepump too).

 

[jdduffield]

So I stuck to the plan and went with an op amp, but another question comes to mind… am I correct in thinking that an op amp will drain a 9v battery much faster than a single transistor?

 

[giovanni]

So I stuck to the plan and went with an op amp, but another question comes to mind… am I correct in thinking that an op amp will drain a 9v battery much faster than a single transistor?

It depends on the circuit and the opamp. I think there are people on this forum who can make an opamp boost that absorbs a tiny amount of current.

 

[jdduffield]

I’m getting a clicking noise when the switch is pressed. I don’t know if it is a pop due to cap leakage or something else. I’m using true bypass wiring. I’m using 1M pull down resistors. I’ve read that this is great for battery life but not great for capacitor leakage and unwanted noise and that 100k is better and quicker response. I think I’ll try 100k pull down resistors and see if it helps. Thoughts?


………..



Just a follow-up. I swapped the 1M for 100k pull down on the output only and it helped a lot. Not perfect, but quite good. If anyone has more suggestions (for helping w true bypass pop/click) please let me know.

 

[jdduffield]

Pictures on my new boost pedal build.

 

[Fama]

I’m getting a clicking noise when the switch is pressed. I don’t know if it is a pop due to cap leakage or something else. I’m using true bypass wiring. I’m using 1M pull down resistors. I’ve read that this is great for battery life but not great for capacitor leakage and unwanted noise and that 100k is better and quicker response. I think I’ll try 100k pull down resistors and see if it helps. Thoughts?


………..



Just a follow-up. I swapped the 1M for 100k pull down on the output only and it helped a lot. Not perfect, but quite good. If anyone has more suggestions (for helping w true bypass pop/click) please let me know.

I hadn't heard of that as a possible fix for switch pop, I'll keep that in mind

 

[jdduffield]

(The schematic for the circuit I ended up using.)