Another awesome contribution Chris Stelloh.
Another 1980's Boss pedal I use a lot, here's the modified layout for the original gray NF-1 Noise Gate, courtesy of Guitar Electronics DIY PCBs in PolanD: SCHEMATIC
I reversed the wiring for the decay pot, since it was working backwards from the original. The LM741 IC is being powered by a 1k resistor-limited supply, so I put the LED+ pad on that rail without any additional current limiting resistors, but if you need your status LED to be dimmer, you can add an extra cut at B23 and place a three column CLR from B22 to B24. As far as the trim pots go, I set the "RNG" to max and the "LVL" somewhere in the middle on my build.
Hey everyone - as far as the trim pots go - you'll want to use the small cermet trimmers, and make sure that you keep the legs away from the jumper underneath since it goes to ground. Also, you'll want to mind the marker on the 2u2 tantalum capacitor, it marks the anode, not the cathode leg.
ReplyDeleteHi,
ReplyDeleteI’ve built the circuit and I am getting the input signal through, but it doesn’t seem to filter any noise.
I’ve double‑checked all the component placements (including the tantalum capacitor), as well as the cuts and links, but I haven’t been able to spot any issues.
@Capitali$t Death Cult –
Did you manage to successfully build the pedal using the diagram above?
Are there any specific requirements or sensitivities regarding the transistors?
Thanks in advance!
BTW, I’m unable to open the schematic link—not sure if it’s just me.
I have built it, it works. I also have an original to compare it to. The schematic for this is the PDF located at the bottom of this sale listing: https://guitar-electronics.eu/en_US/p/NF1-PCB/168
DeleteThanks Capitali$t Death Cult!
DeleteYou are welcome. Also - this layout has a lot of cuts and jumpers - I wanted to get it down to 22 rows so that it would fit sideways in a 125b enclosure - so the board is a lot of work to make. I would suggest maxing the "LVL" trimmer and perhaps trying some different N channel jfets to see if you can get a little more noise gating out of it. Good luck! -Chris
DeleteThis is actually a good pedal, got one of these used back in ‘82, I’ve used it ever since👍🏽
ReplyDeletehey all - I've built a couple of these now and thought I would share some of what I have discovered in the process.
ReplyDelete1) an additional CLR is DEFINITELY needed if you want to connect an LED to supply pin 7 of the LM741. Otherwise the LED takes too much from the IC and the output volume of the entire circuit is below unity.
2) the 2n5485 jfets I have came from Tayda years ago so who knows what they actually are... but I CAN confirm they are jfets, at least, since I have a Peak semiconductor tester. Others that I have also worked (some of which came from Stompbox Parts back before I stopped ordering from that jerk), but also, hard to determine what those ACTUALLY are.
so in order to get this gate circuit to do its thing, you may need a semiconductor tester to find the right bit.
the ones I used measured as N channel jfets with a symmetrical source and drain, with the following on & off voltages:
VGS (off): -2.72v
at ID: 5.0 uA
VGS (on): -.47v
at ID: 5.0 mA
Hope this helps! A noise gate that actually works and doesn't require an unobtanium THAT IC is a good thing to have.