ok, cool, I wasn't quite sure of it.. I haven't built either one yet... so put a cap to ground on pin 5. like in the other schematic, I thought this one might be a little easier to read for some people, you don't really need the second pot either... (r2)
I was thinking that if you did modulate it like a machine gun, it would definitely be audible when the beam hits its target. It would be a strange sound.
I will caution again!!! I beleive Chris allready did... DONT TOUCH THE COPPER ANTENNA while burning.. instant sizzle on the thumb Im branded lol wow You would think a Ham radio operator would know better ooh those rf burns kinda stay with you a while :'(
The circuit is not quite the same...
The first circuit uses pin #7 as the output and only one pot..
while the 2nd circuit uses pin#3 as the output and 2 pots.. :
At 24khz I don't think you would hear it unless there was some lower harmonic frequency
generated..
yep, I was referring to the microprocessor controlled circuit. Although, you could just run this pwm circuit at an audio frequency and you would definitely hear it, as a matter of fact it would probably be so loud it would be very uncomfortable! it would just be strange to hear sound from the beams impact. It would be much louder from the laser itself. Anyone taken any video or pics of it yet? :-?
Breadboard one circuit and watch it on your Oscope. Then try the other to see which one suits your needs. Pins 3 and 7 are almost the same output but may be inverted. Pin 3 can act as a discharge as well as 7.
I agree that 24 kHz is a bit above my hearing range !! Might be fun to try a lower freq ;D
I spoke with Chris about voltage input....... The RF supply likes the upper end (~32 volts) rather than lower. I noticed that the power supply heatsink warms faster as the input voltage drops. Appears to be higher I^2R losses. As my gell cells peter out, the power drops quickly and that heatsink warms faster. The power supply appears to need greater fan cooling.
Mike
OH another thing..... Those copper strips appear to be a tuned split 1/16 wave dipole antenna on the plasma tube. Voltages at the high impedance points could exceed 1,000 Volts. As most HAMS know, RF burns are a B1Tch
I should be able to turn my 28 volt lambda power supply up to 30 volts Im hopeing but I also notice the mo warmer for lower voltage it like a starving ampplifyer
Nightstick --
You have expressed the idea correctly in "down home" terms ;D
I will be using a bank of 18650's for short runs. I think they will put out 10 Amps for those quick demos.
I'm using:
R1 10K Ohm pot
C1 .01 and .022 Mfd caps in series
R2 820 Ohm - This may have to be adjusted down to supply 20 mA drive current when connected to the power supply. Update: a 180 or 220 Ohm resistor shouls work here to drive it.
With this RC timing circuit -- My old junk box parts, I read 23 to 25 Khz output on my freq counter. The O'scope shows a good square wave going from ~ 1% to near 98%.
There are two similar circuits for basic pot controled PWM drivers posted here. try them both and report your results. The programable controlers being designed here will be super for specality drivers involved in engraving etc.
These kits may be outputting a little more than reported. Be Careful.....
Thanks Mike! you made my experimenting with components less work, now I know what to dig out of the parts bin! I don't have freq counter. So, about .007uf for c1?
Those are the cells used in many hybred cars. I intend to use them for short duty cycles. I think they can output 10 Amps for a few seconds at a time. That's all I need !!! I haven't found any ratings but they hold a BUNCH of power.
Mike
Test the used cells for "balance" you don't want to overheat one