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Projects by members => Projects by members => Electrojolt => Topic started by: electrojolt on May 30, 2009, 17:01:27 pm
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This topic is dedicated to provide step by step instructions to assemble my PWM using my PCB
here are the 1st steps:
1st identify the component side of the board:
I recoment using a low power Soldering iron 15 to 30 watt and very thin solder.
Parts needed:
3 555 timers
3 LM311 comparators
1 LM7808 8 volt regulator
2 100uf 35volt electrolitic cap
5 .1uf (104) seramic caps
3 1uf caps
3 10nf (103) caps
3 330pf caps (331)
3 2n2222 or 2n4401 NPN
4 2n2907 or 2n4403 PNP
3 or 6 FCPF11N60 Mosfets get some extra incase you kill some..
4 2.2kohm
13 1Kohm
3 10Kohm
3 100k or 200k or 500K Potenciometer
3 1K Potenciometer
3 10K potenciometer
8 on-on mini togle switches
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Then Solder the Power leads Red and black.
Also Solder the Voltage Regulator LM7808
Stay tuned for the rest, I will be updating this as I assemble this board. I don't have much free time so it will take me a few days.
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Ok, so once the LM7808 and power wires are connected, I add the Filtering caps.
Now these don't have to be a specific value, but a 0.1 (104) and a higher uf value combo will be fine. I usualy salvage them from old electronics.
there are 2 pairs: the set next to the LM7808 is to filter the input power, so the cap voltage rating needs to be higher than the power supply you going to use.
the other 2 pairs, is to filter the 8 volts regulated by the LM7808, so here the cap volatge just needs to be higher than 8 volts.
After the caps are in place, I test the completed circuit Power supply by taking a reading at Pin 8 of the 555 locations.
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Once the Circuit power supply is in place and working, then it is time to solder the 555s and 311s
Pay attention to the chips direction and pins. chips will have a mark to identify Pin 1. LT bottom side of the chip.
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now lets solder some 1k ohm resistors, the color code is Brown Black Red, I have tested 1/8 watt and it works fine, and 1/8 is what I'm using.
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Next I solder some (3) 0.1uf caps, these go between pin 5 and ground on the 555s.
Notice that the caps are installed on the holes closer to the 555s, the other 2 holes are for additional and option 8 volt power filtering.
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Next I solder 3 jumper, initially this spots was to place 3 switched, but then I thought that using a jumper and 2 switched would do the same job and simpler.
So the Jumper will collect the lowest value cap to ground, and the 2 toggle switches will add the 2 other caps to the cap bank slowing the pulse rate (freq) down, this will provide the wide freq range selections.
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Ok, next I solder 3x 2.2 Kohm resistors, you can use up to 3.3kohm. I'm also using 1/8 watt here
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Next I solder the Freq range switches, you can do this last. I like to do it now so I can pre-test the 555s
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Next I solder the Potenciometer(s) that will adjust freq. Here you can use any pot 50K or higher, on this version I tested using 500K pot, it does provide a wide band freq, but it also has a dead section(when resistance is close to 500k) So I'm going to use 100K with a second 1K pot in series. the 1k pot will allow more precision adjustment. Using a higher value Pot will allow a much wider range of freq per Cap. but it will also make it harder to fine tune to a specific freq. that is why using a low value pot in series will overcome this.
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Next I perform the 1st test.
I solder a lead to the test point and connect the scope probe. You want to see a perfect Saw tooth wave.
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A few more steps today
After verifying that all the 555s are generating the Sawtooth wave, now it is time to work on the LM311 sections.
1st I solder 3 0.1uf caps (104), and C4 on the schematic they are used to regulate the adjustable voltage by the variable voltage divider.
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Next Solder a 1uf cap C3 on the schematic,
This is also used to regulate the signal from voltage divider.
Notice the Negative is to the XXXXLeft,XXXX ---- Sorry, To the Right....
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Next I Solder 10Kohm R9, this will feed the signal from the next to be assembled voltage divider.
Next I assemble the Voltage divider by starting with the Resistor that goes to ground R8, here you can use between 1k and 4.7K
Since I don't have anymore 1ks, I do have several 4.7K. Since I'm using 4.7k to ground, I will have to use a higher resistor also to positive R6. and I'm usin 5.1Kohm.
but you can use the ones on the schematic
R9 = 10k
R8 = 1k
R6 = 2.2k
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To Finish the voltage divider and completing the LM311 compatator section I soldered the 10K Potenciometers
Center hole goes to Pot wiper.
That is it for today, more tomorrow
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Next I solder 2 toggle switches that will select the operation mode for 2nd and 3rd PWMs (Stand Alone or Gated)
the Center hole on the PCB goes to the Center tab (common) on the switch.
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Ok, after installing those 2 switches, the Signal generation sections is completed and it can be tested.
If you noticed I'm leaving the C2 capacitor bank to the end so I can show you on how to select the caps, it will depend on the freq range you need...
To perform the test, I just place some caps in place with out soldering them. just make sure the legs are tight agains the holes so they connect.
Now the only thing left is the transistors and Mosfets.
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It is now transistor time...
I start with 3 NPN general purpose transistors like 2n2222 or 2n4401.
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Next 3 PNP General purpose transistors like 2n2907
so this pair of NPN and PNP will work to boost the current from the LM311 to drive the Mosfets.
I called them the drivers.
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Next I solder one more pnp transistor, same as the other 3.
this is used to invert gate the 3rd pwm, so when the second is on, the 3rd is off.
this can be used to trigger the EEC circuit.
Almost done, the only thing left is the mosfets and the optional back emf recovery diodes and cap.
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very neat, you etched it yourelf?
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Alan,
No, I didn't etched these my self, I have done etching in the past, the best method is using a UV lamp, transparant paper, and photo sensitive boards.
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To the last steps:
I solder the mosfets and power wires:
I'm using 2 output wires (orange) per output so it can handle more power.
If you planning to power something that needs more power you can use 2 Mosfets per channel.
3 555 timers
3 LM311 comparators
1 LM7808 8 volt regulator
2 100uf 35volt electrolitic cap
5 .1uf (104) seramic caps
3 1uf caps
3 10nf (103) caps
3 330pf caps (331)
3 2n2222 or 2n4401 NPN
4 2n2907 or 2n4403 PNP
3 or 6 FCPF11N60 Mosfets get some extra incase you kill some..
4 2.2kohm
13 1Kohm
3 10Kohm
3 100k or 200k or 500K Potenciometer
3 1K Potenciometer
3 10K potenciometer
8 on-on mini togle switches
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I forgot to post this 2.2k resistor, it is the link to Gate the 3rd PWM.
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I have my switches on, had to buy a new soldering iron, only burned myself twice.
Truck load of questions for you :) if you don't mind.
1. The Black wires in the corner, what gauge are they?
2. The orange wires, what gauge are they? (is 22 suitable? i have plenty of it)
3. Each of the three black wires is the ground for each channel, and the orange is the positive?
4. When you use two orange wires, they both act as the positive, so you would join both of them to the primary? and a black to the bottom/other end of the primary?
5. The reason for more orange wires is because larger wires don't fit?
6. if i want to send a gated signal to the primary, i am combining channel 1 and 2, so do i hook up channel 1 or 2 to the primary?
7. The red and black wires on the right side in the middle, these are the input from my variac? (or what is a suitable source?)
8. I have 2 power supplies out of old computers, would it be a useful idea to use this and connect a 12 volt output from the c-ps to the input of the pwm?
9. Is this heat sink too big? 3.5x1.5x1.25, half of a CPU heatsink, i could cut more off if you think it is not needed this big, how hot will these mosfets get?
Thanks :)
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No problem
I used 18 gauge wires,
I don't see a problem using 22 gauge specially if you just planing to test with the VIC, since the VIC is not supposed to use a lot of power.
The back wires are the ground source.
the orange wires are the negative output that connect to one side of the primary. the other wire from the primary goes to the positive of your power source.
I personany used 2 orange wires becasue I use this circuit for other experiments, when I drive coils with over 10 AMPS.
To pulse the VIC in gated mode, you use the middle output.
when you use 2 power supplies, you need to connect the grounds of both PS toguether. Shared ground. then one positive goes to the red wire on the PCB, next to the LM7808.
and the other positive goes to the primary on the VIC.
that heat sink looks fine. it is allways better to have bigger heat sink.
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Thanks, I'll probably have some more questions in a few days, but i'm liking how things are coming together.
If you are interested in designing a Frequency Sweeper with a PLL to lock onto resonance, as Stan describes, then i'll be first in line to buy that from you too.
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thanks..
Yeah, that is the reason I build this very versitile circuit so we can experiment and try to find the correct signal to perform the magic.....
then once that is found, I can build one that will do it automatically.
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Can you build an "add on" sweeper and pll that connects into this pwm, or would it need to be a whole new board?
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would have to be a new PCB.
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Right on, I just had a thought, for the frequency sweeper, a nice idea would be to have a variable upper and lower range, maybe with two pot's and some switches, so once you figure out the working range for your setup you can just narrow the sweep range to match, or maybe if it sweeps so fast this isn't even needed, i don't know
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Engineering a pll around a functionning cell is not some walk in the park .
That schematic provided has to be totally re-done .
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Did anyone build this PWM or assembled after purchasing the PCB from Jolt? I still wish the component locations were marked/printed on the PCB for easy solder/placement.
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Where are the 3 resistors on the PCB? Can you please point/label them with arrows?
R9 = 10k
R8 = 1k
R6 = 2.2k
Next I Solder 10Kohm R9, this will feed the signal from the next to be assembled voltage divider.
Next I assemble the Voltage divider by starting with the Resistor that goes to ground R8, here you can use between 1k and 4.7K
Since I don't have anymore 1ks, I do have several 4.7K. Since I'm using 4.7k to ground, I will have to use a higher resistor also to positive R6. and I'm usin 5.1Kohm.
but you can use the ones on the schematic
R9 = 10k
R8 = 1k
R6 = 2.2k
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Today, i repaired the links to the pictures of this project.
I am building one myself now, as this PWM does NOT shift in frequency as soon as you tune the gating.
Its really a fine tool for everybody who wants to discover Meyer secrets.
I will use the 2n3055 transistor in stead off the FET's.
Steve