Need to swap the order of 12 wires - Page 1
Forum section: electronics / projects

author: cowasaki
author_rank: Frequent Contributor
timestamp: October 27, 2019, 07:38:27 pm
content: Ok.... I have 6 pairs of wires which I need to switch to different pre- defined orders. The signal is around 1v or less and there are maybe 10-12 possible orders required. A 12 terminal 10 position switch would do itbut not likely to find such a thing that would fit in the location required (inside a guitar!). So I'm thinking about switching them using another method but can't think of a reasonable way to do it.Can anyone else?IN OUT1 OUT2 OUT3A1 A1 A2 etc etcA2 A2 A1B1 B1 B1B2 B2 B2C1 C1 C2C2 C2 C1D1 D1 D1D2 D2 D2E1 E1 E2E2 E2 E1F1 F1 F1F2 F2 F2

author: mathsquid
author_rank: Frequent Contributor
timestamp: October 27, 2019, 07:52:47 pm
content: Try googling analog crosspoint switch IC.

author: Ian.M
author_rank: Super Contributor
timestamp: October 27, 2019, 07:55:20 pm
content: Yep.If your application can tolerate a couple of hundred ohms on resistance, an analog crosspoint switch could do the job. Ideally 12x12, but you'll probably have to settle for 16x16 due to availability. If you can prune your number of orders down to eight you could use an 8x12 one. It will also need power and a small MCU to read a control input and output a switch control bitmap to the crosspoint switch. The MCU can sleep between input changes so should have no effect on the audio.

author: cowasaki
author_rank: Frequent Contributor
timestamp: October 27, 2019, 09:00:50 pm
content: Thanks a full audio one will probably be needed. It is for 3 humbuckers pickups on one guitar. Each humbuckers is made of 2 single coil pickups so 3x2x2 wires. The sound of the guitar can be changed by swapping the wiring round to have coils working in and out of phase, parallel, single coils etc with additional switching a 12 or 16 by 16 would allow most possible configurations.

author: Tomorokoshi
author_rank: Super Contributor
timestamp: October 27, 2019, 09:03:43 pm
content: Qty. 6 small-format DPDT switches?Something like this?https://www.digikey.com/product-detail/en/e-switch/100DP1T4B1M1QEH/EG2407-ND/378876It would require knowing the "binary" settings for the combinations you need.Do you need to change them on the fly, or only during some setup time?

author: cowasaki
author_rank: Frequent Contributor
timestamp: October 27, 2019, 10:41:58 pm
content: Quote from: Tomorokoshi on October 27, 2019, 09:03:43 pmThat’s not really practical part way through a song on stageI’m liking the above IC. The microcontroller could have a program for the set and then it could be changed with a single on off on non matching switch

author: Ian.M
author_rank: Super Contributor
timestamp: October 28, 2019, 12:14:36 am
content: You don't *need* a 12x12 crosspoint switch. Six coils is twelve leads so you do need 12x something. However, with only six coils, any possible series combo (including any polarity combos) can be constructed with only seven nodes. Any time you parallel coils you save a node. That means you only need a 12x8 switch. That gives you a spare node, so you could take the output from the wiper of a pot connected across two nodes to permit live fine adjustment of the hum-bucking effect. I'm currently envisaging it as a 12x8 crosspoint switch powered by a 12V battery, e.g 4LR44, to get enough headroom as the battery discharges, a micropower OPAMP as a rail splitter to get symmetrical +/- rails for the switch with respect to output lead ground, and a ultra-low quiescent current regulator to power the MCU.

author: cowasaki
author_rank: Frequent Contributor
timestamp: October 28, 2019, 06:21:24 am
content: Quote from: Ian.M on October 28, 2019, 12:14:36 amThat sounds great. I understand most of the last part but not how I can sort it with an 8

author: james_s
author_rank: Super Contributor
timestamp: October 28, 2019, 06:56:14 am
content: What about relays? They can be switched by simple logic in any combination you like, they're relatively inexpensive, have low contact resistance, good isolation, just another idea to consider.

author: gbaddeley
author_rank: Regular Contributor
timestamp: October 28, 2019, 08:09:43 am
content: Quote from: cowasaki on October 27, 2019, 09:00:50 pmGuitar pickups are essential a high source impedance device. The sound is influenced by the resistance of the volume and tone controls and capacitor in the guitar, the lead (capacitive loading), and the input loading of the amplifier. If you throw in active analog switching, amplification and mixing, the sound will change, probably not for the better. Been there, done that. Dynamics and upper treble are affected the most.A suggestion is to use miniature mechanical relays, with a multi-position single-pole switch and diode logic to select which relays are operative in each position. The relays can select in-phase / anti-phase for each coil, which coils are in parallel, and which are in series (if you really need that). You can choose the most interesting combinations using the diode logic.