I have here an FV-1 PCB from PedalPCB. As it is a mono in/out board I have been thinking about using the unused audio input to to a tap tempo input, rather than the usual idea of putting a tap switch across one of the pot inputs. On this board the 2 audio inputs are tied together so I would have to separate that track with a Dremel. I can do that. The problem then is that I would be left with an audio input pin that doesn't connect anywhere, so i would need to probably solder a lead directly to the IC pin from the switch. Those pins are quite small and close together. Is it possible? If so, do you have any tips to make it easier?
Thanks
if you're careful you can scratch of the soldermask of the trace leading to the IC with something sharp and then solder directly to the copper trace.
As far as I can work out the trace is under the IC, which pretty much sits flat on the PCB - there's not much space there. That was my first thought too.
You could also bend 1 of those pins up so it doesn't solder to the board at all, then attach stuff in mid-air, like an old tube amp!
I had not thought of that. It is a pretty good solution to what I need. Thanks. I am usually pretty focussed on not getting IC pins bent out of shape it didn't occur to me that could work in my favour. I will definitely give that a go. As the pin isn't in use anyway it shouldn't matter if it goes wrong.
Quote from: Digital Larry on April 26, 2021, 01:13:38 PM
You could also bend 1 of those pins up so it doesn't solder to the board at all, then attach stuff in mid-air, like an old tube amp!
The other option is to cut the track that runs between the 2 pins of the FV-1 with a razor blade/box cutter knife rather than a Dremel as less damage can occur, then solder a wire to the pin for use. If the FV-1 pin is still connected to a solder pad then you are less likely to break the pin off the chip at any time. Either way works but just pick what you a most comfortable with and that is best for you.
I'd be less likely to "bend the pin up" and more likely to "smash it flat with a pair of needle nose" to prevent it from snapping off where it goes into the body of the chip.
You don't want to ask me about the time I designed a board with an 80 pin chip on it and didn't bother to check the package, so I told the PCB designer to use 20 on a side. When the chips came in they had 15 pins on one side and 25 on the other. I made it work but it was not pretty. This sort of set the stage for my exit from hardware engineering. :icon_mrgreen:
By smash it flat do you mean to make it so that the pin end is up and down rather than flat side to side sitting on the pad?
He means not actually bending the pin but rather straighten out the bend that's already there :)
OK, that makes heaps more sense. Sounds very doable
Quote from: niektb on April 27, 2021, 04:04:36 AM
He means not actually bending the pin but rather straighten out the bend that's already there :)
Yeah, so it comes straight out the side.