Tube Amps / Music Electronics
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|1/3/2001 7:20 PM|
||Re: perfboard newbie question|
Welcome on board to Gadget Univ.
A few additional pointers as far as perfboard wiring goes...
1) Leave LOTS of room on the perfboard. I can't count how many times I snipped off a piece of the stuff and then had to figure out how the hell I was going to fit "all that" in a given corner. You can always snip away the excess to fit the case when you have a layout you like. Perfboard is like maple syrup on pancakes; you always need more than you think you do.
2) Try to conserve component leads whenever possible. Undoubtedly, you will stick something in the wrong place, find out it has to come out and go somewhere else, and then discover that you haven't left enough lead on one side for it to do the job. If you had parts bins stuffed with replacements, no big whoop, but as a newbie it may well be your *LAST* 2.2uf cap or 120k resistor or 1N34 diode. So, as part of your planning out of the board, use as much lead from BOTH sides of each component as you can. That should leave you cannibalizable parts for re-use...after you notice the mistakes. (Been there, done that, bought the T-shirt, and used it to wash the car already.) Trust me on this one, you want to avoid having an almost completed board staring at you for 9 months, while you wait to score that one stinking resistor that you cut too short.
3) Most battery connectors can't hold up to typical use. Make your own 9v connectors by extracting the connector from dead 9v batteries and soldering *decent* red and black hookup wire to them. You may need to scrape the backside of the male and female cups on the connector for the solder to adhere. I find Eveready Classic (the red ones) yield nice firm connector plates but other batteries work fine too. You can insulate the exposed back of these connector plates with some hot glue.
4) While we're on the topic of hot glue, I find it useful to secure wire leads to the perfboard with a dab of hot glue. It acts as strain relief to keep the wire from fracturing due to excessive bending.
5) The wire leads tend to poke out more from the underside of the board than they do in the case of printed circuit boards because of the wrapping of one lead around another. Even AFTER you trim the excess with end nippers (very handy), there is still lotsa stuff to accidentally short out against the case. There are several things you can do to keep these wires electrically isolated from the case or battery. You can secure the board to the chassis with screws and spacers (yet one more reason to leave ample room on the perfboard). You can mount the pots directly to the board and hold the board against the case when the pots are panel-mounted (although that takes some planning). Alternatively, you can buy some sheets of sponge/foam to wrap around the board from a hobby store. It can be held in place with a dab of glue, a rubber band, or sheer friction.
6) If you can, plan your board so that parts which *can* be laid on their side (generally caps and transistors) *are* laid on their side. This will give a lower profile board, let you fit it in more snugly into the chassis, and let you wrap foam completely around the board more easily. It will also prevent those components from being wiggled around enough to snap their leads. If you know the board is 100% functional, you can even use a dab of hot glue to secure those components to the board. I've had more than one perfboard project drive me crazy during troubleshooting because of a hard to see break in the lead of an upright component.
7) Don't be afraid to use jumpers, but don't go nuts with them. Not *everything* in a circuit can fit right beside those components it is connected to. Sometimes, you just have to put things in a kind of out of the way place. Then its time for the jumpers. A great source of jumper wire is the medium thin gauge solid core wire that you find in multi-conductor institutional telephone cables. Next time somebody rewires the phone lines at your workplace or school or whatever, score a couple of line feet of the stuff from the phone installer person. I would strongly recommend against using it to connect pots, switches, and jacks up to the board, since it will easily fracture from bending inside the insulation (where you can't see the break), but the virtual rainbow of insulation colours and striping codes used on these solid core wires makes them ideal for having distinctly coloured jumper wires on the board for different connections. They tin great and wrap around IC socket pins nicely. In the world of perfboard wiring, remembering what goes where and what connections have and haven't been made yet is critical. The colours help you to do that, and the thin gauge lets them sneak into tricky spaces. Try not to let the jumpers interfere with either installing/deinstalling other components or seeing their values.
8) Socket EVERY IC!!! It is one thing to desolder an 8-pin IC from a PC-board, and quite another to have to re-install an 8-pin IC and rewind/rewrap the connecting leads around those pins. If you can score transistor sockets, use those too. There's always ONE transistor whose pinout is different than you expected. Reinstalling is that much easier when it only involves pulling it out of the socket and give it a quarter turn to stick the pins in a different spot.
9) Keep another copy of the schematic handy and use different coloured pens/markers to check off those connections you have made and those which are tentative. It is SOOOOO easy to lose track, especially when you have to knock off for the evening mid-project.
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|1/3/2001 7:50 PM|
Here are my thoughts to Mark's excellent post
>Leave LOTS of room on the perfboard. I can't count how many times I snipped off a piece of the stuff and then had to figure out how the hell I was going to fit "all that" in a given corner.
Especially at the beginning. As you get better, less space will be needed. In fact, start out the right way by sketching the layout on paper - in a notebook. That way you always have a history of your circuits. I'm on my 3rd notebook now. Every circuit takes 2 pages, a layout sketch and the schematic sketch.
Oh, and figure out the maximum size of the board BEFORE you start soldering!!!
> Try to conserve component leads whenever possible.
Yes, never cut until you are sure you don't need the lead anymore. If you cut something too short though, you can use resistor leads to "lengthen" the lead. Use crappy value resistors that you bought too much of.
>Most battery connectors can't hold up to typical use.
Sometimes I take the LED type leads (thicker than usual) and keep them around. I poke them UP out of the pefboard and I solder the heavy duty snaps from mouser.com to them. That way, I can remove them if the snap goes bad - which the heavy duty ones from mouser.com seem to never do.
>there is still lotsa stuff to accidentally short out against the case.
R.G.'s heavy duty velcro tip also works good for this. Holds the boards on pretty darn well.
Here's one last tip - remember you can run leads on the TOP of the perfboard too! Sometimes this comes in handy for that last jumper!!!
|1/3/2001 7:58 PM|
|Steve Daniels (Small Bear Electronics)
I hope you make an article out of your response and post it. Couple of comments:
--You are right about the poor quality of most battery connectors. At Aron's suggestion, I stock one by Eagle Plastics that actually is more robust than most I've seen. More expensive as well, but you already guessed that.
--Re hookup wire: Like you, I learned about 25-pair telephone cable as a teen-ager. Excellent for jumpers and temporary connections to a breadboard. Aron asked if I could find some thin, stranded "tinned-all-the-way-through" wire for pedal internals. After numerous calls (I found that rarity, a salesperson who actually knew something useful!) I have found a source and sent Aron a small sample to try out. He should have it this week and will be able to report.
|1/3/2001 8:09 PM|
||Re: perfboard and sockets|
I read in the old forums about not using sockets[or ar least soldering the parts in] for stage use pedals, but my stuff is always being tweaked to cut through the mix, especially input caps! Endless modding!
So lately I've been using my needlenose pliers to put a few jags in the leads of the caps and trannies, like a wiggle or an S, it really helps hold them in the sockets firmly. You can also pull on it a little after you slide it in and see how firm it is holding. If it is a litle loose, pull it out and put a little more wiggle in the leads.
|1/3/2001 9:00 PM|
Once I get THE sound I was looking for, I "freeze" the pedal. That is, I solder the components to the sockets. Done...Finished...
|1/4/2001 12:15 AM|
|R.G. on the road|
... and when you're REALLY sure it's right, make a little cardboard tray that just fits the board, pour that full of epoxy or polyester potting compound, and settle the board into it. When the potting compound sets, you're FROZEN.
|1/4/2001 5:04 AM|
1. Where Are you?
2. Any projected date of return? Your expertise is sorely missed.
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