My First Pulse Width Modulator Mod

[Java_Az]

Ok i am going to roll with it like is. Circuit looks correct to me also. Might just get it done before the mail lady gets here today.


Here is the photo transfer onto the copper clad board. Time to mix up some chemicals now.

Here is the etch in progress. You can see the solution turning blue cause from the copper getting eaten up.

getting close lots of missing copper

 

[clutchjunkie]

i went back and edited it, should have been pin 1. I had some trouble with using pin 8 when I had it breadboarded up, so I just went with pin 1 and everything worked the way I thought it should. For some reason when I used pin 8 the zener effect never seemed to work. Might have been the way I had the circuit set up, I don't know I was tired

 

[bstedh]

That is sweet work on the board...

 

[bstedh]

i went back and edited it, should have been pin 1. I had some trouble with using pin 8 when I had it breadboarded up, so I just went with pin 1 and everything worked the way I thought it should. For some reason when I used pin 8 the zener effect never seemed to work. Might have been the way I had the circuit set up, I don't know I was tired

We have it on pin 8 so hopefully it will work... Maybe you just had the zener backwards if you where that tired.. ;] If not I will just jumper it out for now.

 

[Java_Az]

We have it on pin 8 so hopefully it will work... Maybe you just had the zener backwards if you where that tired.. ;] If not I will just jumper it out for now.

Might have to since when i set up the multiple layouts i somehow opened the old one with the regular zener layout. Other then that i think the board turned out ok. Going to dril a couple holes make sure both sides are lined up.

 

[bstedh]

Might have to since when i set up the multiple layouts i somehow opened the old one with the regular zener layout. Other then that i think the board turned out ok. Going to dril a couple holes make sure both sides are lined up.

A little creative solder and wire work can fix that...

 

[NicksVap3]

looks like the size of a sim card... those are nice. smart, talented people here. good job guys

 

[Java_Az]

Now with a bit of solder mask. Still trying to work out the bugs on it but it is not too bad.

 

[bstedh]

Java_Az, did you ever get a chance to play with your bread board to see what ohms would give what duty cycle?

I am trying to decide what size POT's to get. I will need to buy one that will give me the range I am looking for in a quarter of a turn. I will probably have to get several sizes to experiment with so I am just looking for a ballpark resistance to start with. These things will probably end up being the most expensive part on the shopping list.

Here is my current order list FYI...
1 50 RNCP0603FTD150RCT-ND RES 150 OHM 1% 0603 SMD 0 0.02080 $1.04
2 20 RHM220DCT-ND RES 220 OHM 1/5W 5% 0603 SMD 0 0.08300 $1.66
3 1 3352W-501LF-ND POT 500 OHM THUMBWHEEL CERM ST 0 1.58000 $1.58
4 5 P12301SCT-ND SWITCH LT 4.7MMX3.5MM 350GF SMD 0 0.78000 $3.90
5 10 BZX84C6V2WDICT-ND DIODE ZENER 6.2V 200MW SC70-3 0 0.28800 $2.88
6 50 311-40.2KFRCT-ND RES 40.2K OHM 1/4W 1% 1206 SMD 0 0.02280 $1.14
7 6 296-16792-ND IC OSC MONO TIMING 500KHZ 8-SOIC 0 0.44000 $2.64
8 10 641-1283-1-ND DIODE SCHOTTKY 100MA 30V 0603 0 0.31500 $3.15
9 10 445-5099-1-ND CAP CER 10000PF 25V X7R 0603 0 0.10000 $1.00
10 6 350-2055-1-ND LED INGAN BLUE CLEAR 1206 SMD 0 0.62000 $3.72
11 50 P220KECT-ND RES 220K OHM 1/4W 5% 1206 SMD 0 0.02420 $1.21
12 10 IRFML8244TRPBFCT-ND MOSFET N-CH 25V 5.8A SOT23 0 0.23000 $2.30
Subtotal $26.22

 

[clutchjunkie]

I was just at the breadboard and I came across something.

R2 isn't necessary.

Using a single 370 ohm resistor for R1 and a 500ohm pot I got a range of 2.8 to 5v according to my free harbor freight voltmeter. This was with a dual coil as a load, and the hits were a little harder than I would expect from that range, more like 3.2-5.5. Pin 6 was connected directly to the pot where R2 was.

 

[Java_Az]

Java_Az, did you ever get a chance to play with your bread board to see what ohms would give what duty cycle?

I hooked it up and was going to do some tests. I decided to put a 330 ohm resistor in R2 just to see what would happen. It would not power up after that so first thing i did was pull my supply wires and test for voltage. Then next for some odd reason i hooked it back up backwards. Anyways i am pretty sure i fried the 555. Did find a dead wire not sure if that was the cause in the first place or it went out with the reverse polarity. Clutch says just a 370 on R1 does good for him. Might want to add a few of those to your order and some 0603 jumpers. I might Just stop by radio shack and pick me up another 555 or maybe two since i like to fry them. I had some things come up yesterday so i didnt get the boards in the mail. But they are done solder mask is a bit on the ghetto side , but better then no mask. Really need to get me a more powerful UV light. Was only my 2nd time working with the stuff. Not as easy to work with as it looks in the videos. Going to get these things packaged up and ready for the mail lady. I will report back if i get a replacement 555.


EDIT: Almost forgot the final products

 

[bstedh]

I think I will get a 500, 1K, and 2K pot to test the different ranges I get with a quarter of a turn.

 

[asnider123]

You guys are way over my head, but thought I would share this with you. I have tried those single-turn pots and really prefer multi-turn screwdriver-adjustable ones like this. You can be much more precise with your settings. And they're tiny and pretty cheap too.

 

[bstedh]

one of those would work however I am trying to get a adjustment like you have on a cigarette lighter so you can adjust it on the fly without worrying if you have a driver handy while your driving down the road at 70mph =]

 

[breaktru]

You guys are way over my head, but thought I would share this with you.

Alan, you have created a monster with this thread.
These guys are really running with the ball.
Great work to all you techies. Fantastic work.

 

[asnider123]

Alan, you have created a monster with this thread.
These guys are really running with the ball.
Great work to all you techies. Fantastic work.

Yes, I am enjoying this immensely and learning quite a lot. Thanks guys!!

 

[clutchjunkie]

one of those would work however I am trying to get a adjustment like you have on a cigarette lighter so you can adjust it on the fly without worrying if you have a driver handy while your driving down the road at 70mph =]

What if instead of worrying about the 1/4 turn thing, you just stuck the thumbwheel out of the back running up and down instead of sideways? You would then be able to adjust it with your finger in mid-hit if need be. The only down side is that it would be prone to "unintentional" adjustment by being put into a pocket, but that is a potential issue no matter how you do it.

 

[Java_Az]

This is what i did to get 50% adjustment at the top end in 25% of a turn of the pot. Put a Jumper across R2 or eliminate it if your working on a bread board . Take R1 out and slap in a diode pointing towards the pot. Then slap in a 100K pot .

Now the problem is i doubt we want full power out of this thing. more then likely are going to want it to go from 35% power to 75 or 80% max.

 

[bstedh]

I stopped at RS and grabbed all the parts to make a test unit before submitting my Digikey order... Just couldn't wait. Man are they expensive... I will be staying clear of there if I can help it. It cost me almost as much to get 1 set of parts as it would to get 10X at Digi...

 

[asnider123]

I stopped at RS and grabbed all the parts to make a test unit before submitting my Digikey order... Just couldn't wait. Man are they expensive... I will be staying clear of there if I can help it. It cost me almost as much to get 1 set of parts as it would to get 10X at Digi...

You are lucky you have a good RS, ours sucks! Everything you need is "special order", besides being too much $$$. I was a RS manager for a couple of years in California (for a company-owned store) and I would have been fired if my store was so badly stocked as is our local one (a franchise inside a TV store) ... a complete waste of time going there!!!

There, did I make my point? They suck and they're never gonna get my business unless they get their act together!!!