My first time here as a poster so forgive me if I make a misstep...
I am building a coil (22swg enameled copper wire, about 500 ft), some 4in inner diameter of the bobbin, 1" wide, will have ~ 450 turns. I am using lacquer to make sure wire is wound tightly and does not move to avoid heating. I am hand winding it, so it is not the neatest coil... hoping that does not matter so much.
I want to give it a lot of power, and wanted to use an audio amplifier for that. According to some online calculator, the coil I am building should give about 8ohms of resistance, which is perfect for my audio amp as it can do both 4ohm and 8 ohm output (automatically adjusts itself).
The reason I want to drive it with an audio amp is:
Building my own amplifier is not easy, and good power supplies are not cheap; the cost of this audio amplifier (used) is lower than some power supplies.
I need to drive my coil with some frequencies, rather than just constant signal, so planning to use audio frequencies for that generated with my audio software (sine, square and such).
I am not very educated on these matters so I would like to hear what your thoughts are on this setup:
- Generate frequencies using my audio software and output that to a pre-amp. It will be a mono signal
- Feed from pre-amp to the power amp. I will make sure that all signal strengths are the way they should be (I am aware that pro audio equipment has different line level values than amateur one for instance).
- Connect my coil to the speaker terminal for one speaker. Even though the amplifier has two channels, it can be bridged, to give me more power. I am hoping that since a speaker is essentially a coil, connecting my coil should work too.
I count with dumb luck and increasing volume on the pre-amp very slowly and checking the heat that my coil produces. If it stays only warm to the touch, I am thinking - it is OK.
Am I being too optimistic or can this setup actually work?
Also, given the above info, what would it take to get the maximum power out of that coil and the whole setup? The goal is to produce as strong a magnetic field as possible.
Thank you for any guidance, and if I am too clueless, I will appreciate pointers to articles or books that you think I should study to understand my idea and its shortcomings better.
ps. Power amp specs: 800W at 8ohms in bridge mode or 250W at 8 ohms in stereo mode It can also do 400W in stereo mode at 4 ohms and 600W at 2 ohms in stereo mode. Max power is 1200W at 4 ohms, bridged.
- There would be no ferric core, only a coil.
- The goal of this experiment is to see what the biological effects are of such a magnetic field, using various frequencies, around 200-2000 Hz, with most of them around 300-700 Hz. This would be similar to Rife experiments who used radio frequencies to, allegedly, kill viruses. Apparently, or hopefully, microbes have a frequency at which they (may) die, and it is with that in mind that I am building this coil. Naturally, for a test under a microscope, the field does not have to be very strong, but for a real biological effect, "in vivo", the field would have to be stronger in order to penetrate the tissues.
- I always thought that the stronger the magnetic field, the more power the coil would consume, which means - more amps or watts, right? (probably wrong :) )
- Voltage gain of the power amplifier is 32.5V/V or 30.25 dB.
- Slew rate is >50V/microsecond or >100V/ms in bridged mode.
- Current slew rate is > 32 A/microsecond at 2 ohms
- Geometry of the coil is not critical, I just built a round one, by hand, and used plenty of lacquer to make sure wires are fixed and cannot move (to prevent losses to magnetic field due to heat).