There’s been some discussions bout DIY pick ups lately so I thought i´d share my two pence of it.
I´ll bump an old idea!
In 2002 I built an upright bass. It was quite a hasty build and not to serious. I needed a pick up and my dear father came up with the idea of using relay coils. I found a couple in a drawer. I then slabbed a ferrite magnet to the top and soldered them together and tested, it worked really well. Some years later I was building an electric violin and came to think about my previous success with the relay coils. So I set up a little test rig, bought a bunch of coils and magnets, and really tried to understand the parameters of the coils. I´m really a novice when it comes to electronics and nothing I did would give me any electrification at all so I gave it all up. By the time there was no info to find on the internet and there still aint much to find on the subject. 407 Bug seems to have experimented some with this on his “Mansion polish” guitar and also Elmar´s tested it.
For me this relay coil project has been shelved, as the violin project. Nowadays I build cbg´s. Also, later I discovered that my tele-cable wasn´t working and therefore (amongst other failures) my tests didn’t work out. Maybe coils were to tiny… I do believe there is a great potential in relay coils though!
I´m bringing this subject up to inspire hpoefully someone to do his own laboratory experiments. Relay coils are small, can be very cheap, and they look really cool when placed side by side, almost like some kind of engine. Has a steampunkish look and it would be really really nice to find out what parameters to look for! When you set your nose down an electronics catalogue and read all the tech- specs u find there’s a lot to examine. As I see it, there are two major parameters to look for when trying to find something suitable. The voltage that the relay coil is built for and the resistance of the coil. probably there´s moore to it...
I didn’t succeed in any of my tests but I can at least tell you about the pick up that’s mounted on my bass, that works. It consists of two coils connected in series. Number one is a 6volt coil and the resistance is 20 ohm. Number two I cannot see properly but it seems like it´s a 24volt relay and the resistance to it is 850 ohm. They are an odd couple. I will later present a small video of it so you can hear it. The signal´s a little weak and my small small amp has to be set to max volume. Maybe a preamp is necessary. On the other hand it works great on my Big amp.
There are many coils out there. Not only the transformers! For instance there’s supposed to be very nice coils in older telephone handsets. Also in old military headsets.
Maybe there could be a group for “alternative coils”!
I´m not going any further with this for the moment but I do hope that someone will and I hope that this is possible. People have been testing this for a while but it seems like that no one is taking it further.
Maybe it´s just a dead end.
/Emlas
Replies
Thank you Skeesix.
It was sheer luck that this combination of coils worked. The smaller coil just hangs in there like an appendix while the 24v coil does all the work. I kind of suspected that but its nice to get it confirmed!
Later I did som trials with some coils that didn´t work out but I wasn´t shure if it were the coils or my equipment that failed. Yesterday I tested my coils again and could confirm that they (still) don´t work and this time I´m shure of that there´s nothing wrong with my cables. These coils have a resistance of 2880ohm each! Three conected in series make up to 8640 ohm resistance all together. Just in the whereabouts of a real pick up! Maybe they are just to small or it´s something with the core that makes them useless. There´a picture of them somewhere on this site.
Anyhow thanks a lot for your input and I ordered that book you mentioned! I´m looking forward to read it!
I've done some experimentation with this, and there is also some good info in the book Getting a Bigger Sound by Bart Hopkin. The coil should be around 1000 ohms or as close to that as you can get - like your 850 ohm coil.
I've found that attaching a neodymium magnet works well as they are stronger, and can make up for an underwound coil.