Here are several measurements while running.What voltage do you read on the (+) end of C5?
Agreed. That must be a good clue but I don't know what to do with it yet....I'd say the M1 gate voltage reading is a bit low; I'd have expected to see roughly 1/2 the C5 voltage reading (assuming 50% duty cycle).
The meter is confounded by the DC there. The meter reads something like 22VAC for the power supply. There are NOT peaks to 22V there. Maybe I'll use a 0.1µF ceramic cap in series with the meter probe to see what shows up then.Also, I'd expect to see little if any AC voltage across C6-- not 10.9 volts.
That should work, though a bit more capacitance would be better.The meter is confounded by the DC there. The meter reads something like 22VAC for the power supply. There are NOT peaks to 22V there. Maybe I'll use a 0.1µF ceramic cap in series with the meter probe to see what shows up then.
I've only had a quick look at the schematic, but isn't the voltage at the junction of the output transistors a square wave switching between 0V and 12V, so isn't this is 6V DC with 6V RMS AC imposed on it? What am I missing - how are you supposed to get 12V AC from this? To get 12V AC wouldn't you need an H-bridge?This is working on breadboard EXCEPT that I'm only seeing 6VAC on L1 and 60VAC across L2 instead of 120V. I need some help fixing that.
Duh. I can't believe I missed this!I've only had a quick look at the schematic, but isn't the voltage at the junction of the output transistors a square wave switching between 0V and 12V, so isn't this is 6V DC with 6V RMS AC imposed on it? What am I missing - how are you supposed to get 12V AC from this? To get 12V AC wouldn't you need an H-bridge?
I tried using a 2.2µF capacitor to couple and the apparent voltage across C6 fades down to 5.2VAC.That should work, though a bit more capacitance would be better.
Yes.I've only had a quick look at the schematic, but isn't the voltage at the junction of the output transistors a square wave switching between 0V and 12V...
Awww crap, I've made this booboo before and now it's bit me again. The simulation shows the voltage out of L2 going from +60 to -60 and I was thinking that was 120V but of course it is not. The tests of wall warts in the linked thread show the same thing. The data has been right in my face all along and I missed it....so isn't this is 6V DC with 6V RMS AC imposed on it? What am I missing - how are you supposed to get 12V AC from this?
Looks like it!To get 12V AC wouldn't you need an H-bridge?
Don't feel bad; we've all had moments like that...Awww crap
Sigh ... now looking up H-bridge circuits.Don't feel bad; we've all had moments like that...
Or you could take the circuit as-is and drive a 6 VAC wall-wart with it.Sigh ... now looking up H-bridge circuits.
Yeah, I’ll dig through my box-o-warts but I don’t think I have one. I might have a 9V. Loving the EL glow!Or you could take the circuit as-is and drive a 6 VAC wall-wart with it.
Found one! I had a small 4.5VAC, 120mA transformer. At ~110Hz (low A string on a guitar) and with the EL tape lit, I see about 135VAC at the EL contacts. If I crank up the frequency to 330Hz (high E string), the voltage sags to 110. Backing off a little brings the voltage back up to 125VAC. The circuit is drawing about 60mA from the 12VDC supply.Or you could take the circuit as-is and drive a 6 VAC wall-wart with it.
Yeah, I have a box with a few transformers pulled out of appliances over the years. I'll have to dig through. But things are looking pretty good in the meanwhile. I'll probably commit my little switcher to a protoboard.You could get more voltage by using a transformer with dual primaries; these are usually used with the primary windings in parallel for 110 volt operation, or in series for 220 volts. Something like this.