DIY Effects

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ryanmaiden
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Re: diy effects

Post by ryanmaiden » Mon Feb 18, 2008 12:02 pm

I've made a few D.I.Y effects back in my guitar playing days, I actually used one as a Design Project for a Polytech course. I've done a couple booster pedals which were just simple single opamp circuits. I also made a tube screamer clone which sounded pretty wicked with my Les Paul into my Mesa head. I've put true bypass circuits in all the pedals I've made using relays to switch the signal path so that when I'm not using the effect, my crappy proto-board circuits don't interfere with the signal. There's heaps of circuits on the net, so if you want to give it a go, all you really need to know is how to use a soldering iron, as all the parts, theory etc are all well documented.

A couple of little tricks I have learnt making my own effects are:

Twist signal and signal ground wire pairs together to reduce noise interferrence if you are not using shielded cable, this trick also works with the pickup wiring in your basses etc. An inconsistent twist is actually better than a nice tidy consistent twist as varying twists will have a broader frequency attenuation range (yeah I know, that's getting a bit geeky and anal).

Decide on the enclosure BEFORE starting on the innards, so you know it will all fit.

Signal ground and chassis ground should only be connected at one point (look up "star grounding" on the net).

Double check and then check again before powering up the first time, especially for power to ground shorts, they make batteries get really hot!!
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john
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Re: diy effects

Post by john » Mon Feb 18, 2008 1:21 pm

some good tips there ryan

ryanmaiden wrote:I
Signal ground and chassis ground should only be connected at one point (look up "star grounding" on the net).

!
what do you mean by one point ? because my pedals are in a steel enclosure , so the ground touches the jacks and pots.

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ryanmaiden
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Re: diy effects

Post by ryanmaiden » Mon Feb 18, 2008 3:28 pm

Hi John,

That's cool having the pots etc mechanically grounded to the chassis, but the chassis ground should only connect to the signal ground, ie, your circuit, at one point. If both your jacks are mechanically connected to chassis ground, and you have wires off both of them to signal ground, a ground loop is created flowing through your circuit and back round through the chassis. I tend to use jacks that have plastic bodies and mounting hardware, to keep the signal ground isolated from the chassis ground at these points. I keep the signal grounds isolated from the chassis right up until the completion of my circuit, then I'll solder a wire from the ground terminal of the output jack to the chassis.

A lot of guitars and basses suffer noise problems because of shoddy wiiring practices where signal and chassis ground have been all mixed up. A lot of instruments will have signal grounds soldered to the back of pots (chassis ground), which will then link back into the circuit, then go to the jack, which will be connected to a signal and chasis ground elsewhere, causing a ground loop.

Some people get around the chassis vs signal ground issue by using plastic enclosures and not worrying about chassis ground at all, but this means your circuit is much more suseptible to interference as you don't have a nice big grounded metal enclosure around your circuit.
Hope this all makes sense, let me know if you need any clarification.
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john
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Re: diy effects

Post by john » Mon Feb 18, 2008 4:17 pm

thanks for taking the time to do such a good explanation .
not sure i fully understand the loop part being a problem. sounds like i have done this.
i'll explain how i have my grounds wired .; ground from input jack>---to a ground strip on the PCB (vero strip PCB)>--gain pot 3rd lug>--tone pot 3rd lug>--strip on PCB>---emitter from tranny to the same strip>---volume pots 3rd lug to same strip.>---strip to out put jack. so every thing is going to the same place
so that would be creating that loop you where talking about , yes? what problem should this be making?
thanks. john
edit : here is the link of the fuzz im talking about. i did version two (V2) http://www.home-wrecker.com/bazz.html
and the tone circuit. this is quite a cool one ( bottom of page)http://www.muzique.com/lab/swtc.htm

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ryanmaiden
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Re: diy effects

Post by ryanmaiden » Mon Feb 18, 2008 6:23 pm

Yeah, you'll have a loop because both jacks are connected to the circuit board and chassis, but don't worry about it too much if you aren't getting any noise on your signal.

The reason why ground loops are a problem is because the electrons returning to the battery/power source have more than one path they can take. In this case, they can take the quick route along the circuit board to the battery, or go right round through the chassis and then back up on to the circuit board to the battery. From what I vaguely remember,the issue with this is that it can create slight voltage differences between two surfaces which are supposed to be at the same voltage (0V). And by some sort of elec-trickery, this creates noise.
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Re: diy effects

Post by john » Mon Feb 18, 2008 6:50 pm

just realized after your post that i forgot to say that the batt ground is going to the same place too.
but like you said "not to worry if there is no noise, its quiet as a mouse, until i play something, then it is brutal . which is cool for such a simple circuit
ill keep what you have said in mind for my next builds trouble shooting .
just so i am clear where would you put the batt ground and input ground if there was a problem?
thanks for your knowledge ryan

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Re: diy effects

Post by ryanmaiden » Mon Feb 18, 2008 7:35 pm

Battery ground and input ground in this case are signal grounds so should both go to the circuit board. Are you using the input jack to switch the battery on and off? If not, I'll explain how to do this, and in case others are interested as well:

Using a 1/4 inch stereo socket rather than a mono socket, you solder the hot signal wire from the circuit to the terminal that connects to the tip of the guitar lead as you would with a mono jack. Solder the battery clip black wire to one of the other terminals, and your signal ground wire from the circuit to the last terminal on the socket. The red wire from the battery clip goes to your circuit board as per usual. The battery connects to the circuit when you plug your guitar lead in, as the body of the guitar lead shorts the 2 ground terminals together, closing the circuit and turning the battery on, just like a bought one! Just make sure that the battery wire is the ONLY wire on the terminal it is soldered to.
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john
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Re: diy effects

Post by john » Mon Feb 18, 2008 8:17 pm

ryanmaiden wrote:Battery ground and input ground in this case are signal grounds so should both go to the circuit board. Are you using the input jack to switch the battery on and off? If not, I'll explain how to do this, and in case others are interested as well:
when i said batt , i should have said 9v instead as im just using an adapter , was going to do both but jcar had none and dick smith only had ones where the ring and sleeve poles were not in line . so no touching to break the circuit . batteries are a pain in th ass anyway .

ryanmaiden wrote:Using a 1/4 inch stereo socket rather than a mono socket, you solder the hot signal wire from the circuit to the terminal that connects to the tip of the guitar lead as you would with a mono jack. Solder the battery clip black wire to one of the other terminals, and your signal ground wire from the circuit to the last terminal on the socket. The red wire from the battery clip goes to your circuit board as per usual. The battery connects to the circuit when you plug your guitar lead in, as the body of the guitar lead shorts the 2 ground terminals together, closing the circuit and turning the battery on, just like a bought one! Just make sure that the battery wire is the ONLY wire on the terminal it is soldered to.
awesome tutorial dude. i wondered how pulling the lead out stopped the batt draining for years until resent

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Re: diy effects

Post by ryanmaiden » Tue Feb 19, 2008 5:58 am

john wrote:batteries are a pain in the ass anyway .
So true dude, I've never had batteries in anything that was in my signal chain, until I got an active bass. I think EBS bass amps have a 9V output to power active basses, you just chuck a stereo socket in your bass and use a stereo lead, and it sends the 9V up the spare wire in the stereo lead, now that's handy!
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Re: diy effects

Post by john » Fri Mar 07, 2008 5:33 pm

just made a clean boost pedal for gat mate . here is a pick if anyone is interested
boost.JPG
boost.JPG (77.13 KiB) Viewed 4907 times
inside boost.JPG
inside boost.JPG (91.17 KiB) Viewed 4905 times
and one of my bass fuzz
fuzzy.JPG
fuzzy.JPG (25.48 KiB) Viewed 4905 times

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Re: diy effects

Post by ryanmaiden » Sat Mar 08, 2008 6:48 am

Dude, your enclosures are awesome!! I've never really thought to use anything other than project boxes from jaycar, you must get lots of comments at gigs with all your biscuit and lolly tins on the floor. Kiwi ingenuity at it's best.
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Re: diy effects

Post by beagle » Sat Mar 08, 2008 3:26 pm

true... they are awesome boxes.. love the Fruit Drops!
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john
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Re: diy effects

Post by john » Sat Mar 08, 2008 6:45 pm

ryanmaiden wrote: biscuit and lolly tins on the floor.
:lol:
thanks for comments guys. haven't done any gigs with em yet

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Re: diy effects

Post by joppo » Sun Mar 09, 2008 3:11 pm

I can just see it now... All our mothers will be locking up their old cake tins, and we will be discussing whether a Huntley Palmers tin is better than a Fruit drops tin :D

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Re: diy effects

Post by beagle » Sun Mar 09, 2008 7:45 pm

hmm I wonder if metamucil ever came in a tin? :lol:
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