Small AC VFD?

You -might- be able to drive it with an audio oscillator and amplifier feeding into the speaker side of a 70V audio line transformer. Don't use a power transformer, it won't handle kilohertz frequencies.

jw

I doubt that motor drives will work for you, nowever, I have several drives, rated for single phase and for three phase, 1/2 HP, and up. They are for sale.

i

instead of looking for motor drives, look at the specs for the 555 chip - this will meet your needs

According to steamer :

Well ... Mitsubishi has a tiny one (single hand holdable) which will run from 120 VAC single phase, and produce 240 VAC three phase to drive a 1/8 HP motor.

But part of the question is -- what range of frequencies do you need? I got this one hoping to use it to drive some aircraft gyrocompass and artificial horizon devices -- but discovered that unlike the larger ones, which would go up beyond 400 Hz, this one would only go to something like 120 Hz. I'm still looking for a three-phase motor of the 1/8 to 1/4 HP range to drive from it, to hang on the Taig lathe.

Back when I got mine, it was from eBay at a price of around $45.00 IIRC.

Enjoy, DoN.

apparently my posts aren't making it through Teranews again - anyway, I had attempted to say:

instead of looking for motor drives, look at the specs for the 555 chip - this will meet your needs

as I recall, EL panels use almost no current so you may well find that the 555 alone can do the trick. and the chip is cheap, 5 cents to 25 cents in single quantity the last time I looked

bill

The oscillator is easy but look at the voltage required. I'd try a

70.7V PA amp or fake it with the circuit I mentioned above.

jw

--Thanks; sounds like a 555 is the simplest solution. I'll take a look at the schematics if I need more driving power.

you can run a 555 at about 30 V (off the top of my head), you can drive an old audio transformer backwards, to get higher voltage, or use a single HV low current transistor to switch higher voltage (I did this with 600V on the deflection plates of an oscilloscope tube years ago)

If you are just hacking around and don't need to build this as finished box. Then I think the easiest way to get there is to:

1) Get this or other software like it --- 's an audio oscillator program for your PC that outputs sine waves from the audio output of your sound card. I have not tried this program but only did a search for "oscillator program" on Google. I'm sure there are plenty of these out there however. 2) hook the audio out of your PC to a stereo or any audio amp (all you need is one channel - everyone's got an old stereo lying around - right?) 3) Hook an old transformer (like 110V to 12V or 6V) up to the speaker output of the amplifier. Connect the 12V side to the amp the and 110V side will be your output. Note that the frequency response of any old ac transformer will be fine for this purpose. It's not golden ears audio. I have used these transformers for real audio in a pinch (old TV repair days) and they work fine at much higher frequencies than people realize.

You can dial the frequency on you PC and adjust the amplitude with the amplifier's volume knob. Note that you can get some pretty high voltages this way. At full amp volume, you might get 40 VAC at the speaker outs, then after 12x on the backwards transformer, that can be

500V. The EL wire might need only a 100V or so, so start with the volume down. it would also be a good to affix a multimeter to the output so you can constantly monitor the output, but you might need a better than junker meter to read the correct voltage at higher frequencies than 60Hz.

This might be a bit a involved, but if you've got this stuff around. It will be free and very adjustable.

If you are serious, try a real power amp,. These are $105 each, maybe a cheaper lower-powered one will be enough.

jw

A VFD is probably a bad choice. They typically work at a fundamental frequency higher than 60 Hz, switching that wave on and off in various fashions (i.e. PWM or PCM) to emulate the lower frequencies. The motor load filters out the higher frequencies.

Since the EL wire responds to frequencies up to 5 kHz, you might find that the switching frequency of the VFD is dominant. So no matter how you dial the frequency setting on the VFD, the EL wire may act the same. You could add a big inductor to the circuit to filter out the high frequencies, and the EL wire might work as advertised.

I left a lot of stuff out, so my explanation is probably not crystal-clear. But I'd advise against investing in a VFD unless you can try it with your EL wire first.

--Aha! Good to know B4 I spend the big bucks, heh. Thanks to one and all for the input; experiments to follow shortly..