Messages

My approach would be to breadboard it and see what happens.  But that may be a bit difficult, as you have to try it out in a shop somewhere? 

I think it would work, for what that's worth. :-)   If the LED is working at the moment, just at the wrong time, a 'not' gate should do the trick.  Although you may have to supply power to the LED from somewhere else if the relay is cutting the power to the footswitch when you want it on...? Which would mean a battery in your box just to power the LED maybe? 

If the reverb switching works, but the LED is showing the wrong state, I don't think it's your wiring causing the issue.  Sounds like the relay is set up at the other end to send voltage when the effect is off. 

You could get around that by using a transistor to make a 'not' gate, and hook the LED up to that.  That would reverse the state of the LED anyway. 

Hi Joe,

Assuming you use 9v supply, the resistor will be taking 5.8 volts, you want 24mA max, so you'd want

5.8 / 0.024 = 241 ohms resistor. 

A 200 ohm will be super bright.  400 ohms would be nicer I reckon, and yes, you put two in series to do that.  I usually use higher value resistors, as the LEDs these days are super bright.  Even a 1k or 4.7k would be fine I reckon. 

There's heaps of tutorials on the net about how to calculate the resistor needed for an LED - here's one for example: https://www.sparkfun.com/tutorials/219

As for parallel resistors, that's another thing you might want to read up on.  Two 200 ohm resistors in parallel would be 100 ohms total resistance.  More reading:  https://learn.sparkfun.com/tutorials/series-and-parallel-circuits

For the resistor value, R1 is a 'current limiting resistor' or 'CLR'.  It's basically there to make sure the LED doesn't get too much current and burn out the LED.  1k is enough to stop the LED burning out, but still make it reasonably bright.  You could probably use anything from 500 ohms to 10k, depending on the LED. 

I suspect 100k or 200k would be way too much, and your LED would be very dim.  But it really depends on the specs of the LED.  If you've got a breadboard you could stick them in and test the LED + resistor combination before soldering...? 

The wattage, as you mention, won't really matter that much in this case. 

Nice! 

That's some good jack mangling, I must say.

"I like big knobs and I cannot lie,
You pedal builders can't deny,
That when a pedal in a 1590B
Has anodised knobs on it's face
You get sprung..."

...and wow... I just read the rest of the lyrics to that song.  Can't say I listened that closely before! 

My 9 year old enjoys helping out - partly because he is the one who gets to play with the finished pedals, but he also seems to enjoy the building.  I get him to populate the boards by giving him the part and telling him "Ok this one is R37".  Once he has populated 3 or 4 resistors or caps I'll get him to do the soldering, and then I do the snipping of the leads.  I discretely check that he is putting things in the right spot as he goes. 

So far I'm only getting him to solder resistors, caps and sockets.  Nothing that too much heat will kill, just in case he gives it a little bit too much. 

He's happy enough to do half an hour or so at a time, and we've done a multiplex echo + reverb pedal, and a fuzz face pedal together.  Good way to soak up some weekend time.  We've got summer holidays coming up soon in Aus, so I'll have to get some more PCBs ready to go. 

If you have a look at the data sheet for the LED, it should tell you if the red and blue have different voltage and current requirements... in which case you would need a different resistor value for each '+' leg.

The RGB ones that I've used definitely have a different voltage drop on the red part. 

What I would try would be to connect the common ground pin to any ground (doesn't matter where - ground is ground, no matter where it is on the board), and then put a resistor between the red LED leg and the '+' for pulse, and a different resistor between the blue LED leg and the '+' power indicator.  If there are already current limiting resistors on the board, they may be all you need if they are on the '+' side of the LED. 

Try it out on a breadboard first if you're not sure, so you don't have to unsolder lots of stuff (and if you blow an LED, you can try again easily!)

I've been trying Fritzing to do PCB layout ... I found it a bit frustrating first try.  Couldn't work out what it was doing with the ground connections.  I'm sure if I rtfm it would make sense. 

Awesome theme - love it. 

+1 for the knobs - where do you get them?

Here's one site I've found to be helpful - it takes you through the steps of building a guitar, and has dimensions and things that you might find useful:  http://www.monsterbass.nl/index.html

+1 to the templates.  I'm spending a lot of time getting templates for the body and pickups right before I do the final routing on the block of wood. 

The idea of doing the body doesn't worry me too much, but building the neck myself is another level of stupid.  I need to get the shape of the neck right, the truss rod installed correctly, the fret board levelled and with the correct radius, and then not mess up all the fret cuts, fret filing and fret levelling.  A pre-made neck would make it a lot easier, I guess it depends on what sort of woodworking you want to do, and how pedantic are you and your friend about doing it all yourself. 

Haha, yep.  It is basically going to be "This is a resistor.  It resists the flow of electricity.  This is an LED.  It lights up if you put it in the right way.".  I'll try to cover capacitors, diodes and transistors quickly, at a really high level.  Then throw them into building a pedal with minimal components, and give them plenty of time and help. 

I'm not going to go anywhere near teaching them how to wire up a 3PDT switch.  That's for the extended materials.   

Thanks people...

I was planning on giving them a choice between single transistor pedal with 2 or 3 diodes to build on bread board, or an NPN fuzz face.  They seem to have small enough part counts.  I'm now thinking I'll just give them the one choice, with parts to make the other when they get home. 

Sounds like preparation will be key.  I'll get all the resources and hints available for them to take away, rather than trying to squeeze it all into the workshop time. 

I'm hoping that the conference organiser can give me an idea of the attendees skill level before hand, that will probably make a difference as to how I pitch it.  No point teaching them what a battery is if they have all already done some electronics. 

Thanks Paul - I'll send a PM.

I'll be running a pedal building workshop at a conference in Brisbane (Australia) in December.  It will be a basic introduction to electronics, and then build a simple distortion or fuzz face on breadboard to take home with you.  Followed by info on where to buy components, enclosures, PCBs, etc, and where to find help from friendly people - i.e. this forum.   

Anyone in Brisbane area might want to check out the conference:  http://auc.edu.au/createworld/sessions/.  It is aimed at creative types.  They've also talked me into running a session on Arduino and music, so time to brush up on my MIDI commands. 

Has anyone here run pedal building workshops before?  I'm interested to see if you think I'm trying to cram too much into an hour and a half.  I've done programming sessions at conferences before, but this will be the first electronics / pedal building one I've tried. 

We had 7 kids knock here in Canberra.  They'd made an effort with the fake blood.  I did carve a rockmelon into spooky head and stick it on the letter box, so that might have attracted them.