Electrojolt's Stable PWM Step By Step Assembling Instructions

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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.