| Spasticteapot |
The design is pretty simple; it's a Chill-Amp with 100uf capacitors in place of the 1000uf capacitors, 0.1uf MKT's bypassing the 100ufs in place of the 1uf from + to -, and designed to be powered by a "CarlosFM" snubberized PSU. It's nothing special, as far as Gainclones go.
I have, though, managed to create a simple 1-sided PCB with really big copper traces. I've got access to unetched PCB and ferric chloride, so making them should be no problem, and I can afford to spend some time drilling the holes.
I was hoping to let you have a look; however, the PCB's still stuck in Eagle format. Anyone know how to export it to Jpeg or a bitmap?
Thanks,
Joe. |
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| pinkmouse |
| If you look in the drop down menus, under export, there is a bitmap option. ;) |
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| Spasticteapot |
| Here's the PCB. You can (sort of) see how its laid out; the .1uf MKT caps are soldered directly across the leads of the 100uf caps. The holes in the center are the output, those on the left for the power, and those on the right for the 4.7uf input cap. It's not the best design ever, but I just learned how to use the software. |
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| Greg Erskine |
Hi 'teapot,
Have you generated the PCB from a schematic? Some of the connections to the LM3875 seem wrong to me. V- should be pin 4.
It looks to me like you missed the 22k resistor from in+ to ground and the input cap should be in series with the in+. You need to look at power ground.
I might not be squinting quite right. :D
regards |
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| Spasticteapot |
| quote: | Originally posted by Greg Erskine
Hi 'teapot,
Have you generated the PCB from a schematic? Some of the connections to the LM3875 seem wrong to me. V- should be pin 4.
It looks to me like you missed the 22k resistor from in+ to ground and the input cap should be in series with the in+. You need to look at power ground.
I might not be squinting quite right. :D
regards |
The 22k resistor will be soldered directly to the leads. You're right about the other two mistakes, though; I'll have to fix those!
Can anyone reccomend a possibly neater way of doing this? My implementation seems a bit messy. |
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| pinkmouse |
| Quick glance - the PSU caps need to be as close to the power pins as you can get them. |
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| Spasticteapot |
| Yet another version! |
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| dfdye |
| Careful of the short between the V+ pin and the output pin. That will cause you more than a few headaches in the future! :D |
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| Spasticteapot |
| quote: | Originally posted by dfdye
Careful of the short between the V+ pin and the output pin. That will cause you more than a few headaches in the future! :D |
Oops! I'll have to fix that. (I figured I'd just seperate them with an X-acto knife.)
Any thoughts? I'm hoping to make them up on Monday; I've got access to all the stuff I need, including some rather high-quality PCB material.
Also, can anyone reccomend a good way to drill all the @#$#$ing holes? |
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| Nordic |
| Those holes will kill ya.... I start them off with a small hand-drill just to form the indentation on the right places, then I put the small handdrill in the electric drill's chuck and complete all the holes... |
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| dfdye |
I use a drill press and "cheat" by bringing the table close to the drill bit (~1/2 inch) and setting the depth to just into the backer. That way all you have to do is make short motions to drill the holes and you can be a little more accurate. I also usually wear goggles for this instead of my regular shop glasses since I like to get my head in rather close and a couple of stray shavings almost got around my glasses once. The trick is taking in really slow for the first several holes to make sure you get a feel for it. I'm not sure I could do it with a hand drill!
If you make sure that the areas to be drilled are etched out, it forms a little drill guide that minimizes the drill walking, which will be a major problem with such a fine drill if you don't have some sort of guide.
Are you using photo transfer to make the boards? |
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| Spasticteapot |
| quote: | Originally posted by Nordic
Those holes will kill ya.... I start them off with a small hand-drill just to form the indentation on the right places, then I put the small handdrill in the electric drill's chuck and complete all the holes... |
I think I'll try a very small jewler's automatic center punch, and a dremel with a tiny drillbit. It's what I use for tiny holes in silver, anyway.
I'm going to try the "laser printer-on-glossy paper" method for transferring the PCB resist. However, due to the simplicity of the design, I can (if necessary) just make a stencil and spray on a resist, or use a sharpie. I've got resists, PCB (dual-sided), and FeCl; I should be set to go. |
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| Spasticteapot |
Well, the parts should be ordered by the end of the day. Woo!
And now, for something completely different; I'm going to try and design a discrete buffer PCB a la' Decibel Dungeon.
NOTE: Moderators, would you mind changing the topic to reflect this?
Also, once I've tested the PCB, would anyone mind putting the design up on a webpage somewhere? It's simple, small, and can be used with lots of different cheap components. |
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