I was surprised to find what I did. I actually didn't get quite everything needed but I have enough parts from scavenging motherboards to fill the gap..
My First Pulse Width Modulator Mod
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I was surprised to find what I did. I actually didn't get quite everything needed but I have enough parts from scavenging motherboards to fill the gap..
Yeah Rat Shack is over priced for a lot of their stuff unless your lucky and they have a bulk package of what you need.The prices on bulk are usually not too bad. 2 bucks for a 555 that i could get at digikey for 40cents but i have a RS less then a mile from me so it does come in handy at times but i really try not to go there unless i really cant wait. Especially hate how they always trying to sell you something , well that wasnt so bad till the hot chick that worked there quit.
I got this thing to show a output voltage under load. Not loaded i just get the supply voltage. I might play around with it some more later today.
I got this thing to show a output voltage under load. Not loaded i just get the supply voltage. I might play around with it some more later today.
Funny you mention attractive salespeople .. my store's sales doubled when I hired a beautiful salesgirl. Though it seemed like all the customers wanted stuff off the top shelf.
I just put together my test circuit on a protoboard and it seems to fire full out no matter where the 500 ohm pot is set. I'm thinking either the diode is backwards or the fet is staying latched.
Don't forget, it IS full voltage, you are just adjusting the duty cycle. A meter that's not a TRUE RMS meter may show it to be 7.4 all the time. I did notice, inmy experiments, that with the diode one way, it read ZERO, the other way it read FULL .. until I put an atty on it for a load.
Like I said before, you are the gurus of PWM, I am just a fly on the wall, just thought this may explain the prob ???
:] i haven't even put the mm on it yyet, just a carto and it is burrning the crap out of the juice no matter where it is set. I will be trying fthe mm in a minute, i think it is rms capable??
Yeah cathode or striped side towards pin 6. What kinda fet you got on that thing ?
Need to make sure the wiper on the pot is going to Pin 7 also
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Ok, it apears to be working... The meter seems to be RMS and I think everything is wired correct. With a 500 ohm pot I am getting between 4.9V and 6.3V both are too hot for my BWB Cola... With a 1K ohm POT it would not fire for more than a second and then cut out...
200 ohm pot still only lets me get down to 4.9V... I think my 14500's are unable to handle the current on the DC carto... I am assuming the protection circuit is what is cutting out when I try the DC...
Any Ideas what I could change to get the voltage range down?
Any Ideas what I could change to get the voltage range down?
On the bottom left you can just make out R2 which is an smd 150 ohm resistor.
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Looking at my last picture I just figured out what my problem is... I have pin 2 jumpered to pin 7 and it's supposed to go to pin 6!!!!
fixed the jumper and it worked at first. It adjusted from 1.5V up to 6.9V. After that it stayed at 6.9V. I am going to put some pull up resistance on the fet and see if that will help.
Is the FET latching or is the 555 going into runaway self-oscillation (I think That's what they call it)?
I am going to put some resistors on this afternoon to see if it is the fet. As far as the 555??? I would probably need an O scope to see if it is having an issue. My MM has a frequency meter for duty cycle but I don't know if it will read that high of a frequency. I will give it a try later to see what it reads.
I have to work on it when the wife isn't around otherwise she gets annoyed because I am not paying attention to her of helping her clean or something....
As a side note BWB Cola is pretty awesome! I can't wait to get this thing working correctly to taste it on VVPWM.
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Happy Happy Joy Joy!!!!!
47K across the fet fix the issues. WOW does that thing hit hot. I had to turn my DC down to 2.5Vrms or it was burning my BWB casablanca... Going to try cola on a 3 ohm next...
I just might have to make my first "BOX" mod to throw this test board into. I will have to find one to hold 2X 18650's as the crappy 14500 ultrafires are about worthless.
47K across the fet fix the issues. WOW does that thing hit hot. I had to turn my DC down to 2.5Vrms or it was burning my BWB casablanca... Going to try cola on a 3 ohm next...
I just might have to make my first "BOX" mod to throw this test board into. I will have to find one to hold 2X 18650's as the crappy 14500 ultrafires are about worthless.
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