Stompbox Base Unit

[linny1982]

Ok dano now your pics have convinced me i could make/use something like this (had a mental block on how to work it out). As soon as i get some spare cash I'm gonna give it a go

[MoltenVoltage]

That's great work Chris.

The PCB header idea is key.  If the future PCBs are going to be floating around inside, I recommend coating the inside with electrical tape, just to be safe.

Also, you could make a standard PCB for the three pots with a header, so you can re-use the same pots for different effects if you want to, and not have to swap them out unless you need to.  Standardize it with the LED too and a standoff so you can change LED colors if you want.  If you are really ambitious, set it up for 2 color LED.  A 12 pin header should do the trick.  The circuit PCB could connect to the pot header and the switch PCB header at a standard distance which would make designing drop in PCB's a breeze.

You might also want to consider a 1/4" jack for an expression pedal or tap tempo control on the main PCB.

[JKowalski]

That's great work Chris.

The PCB header idea is key.  If the future PCBs are going to be floating around inside, I recommend coating the inside with electrical tape, just to be safe.

Also, you could make a standard PCB for the three pots with a header, so you can re-use the same pots for different effects if you want to, and not have to swap them out unless you need to.  Standardize it with the LED too and a standoff so you can change LED colors if you want.  If you are really ambitious, set it up for 2 color LED.  A 12 pin header should do the trick.  The circuit PCB could connect to the pot header and the switch PCB header at a standard distance which would make designing drop in PCB's a breeze.

You might also want to consider a 1/4" jack for an expression pedal or tap tempo control on the main PCB.

I am planning a couple different probable changes to the unit before I start making boards for it. I am anxious to use it, but I want to get the whole convention perfected since this will be a sort of "standardization" for me. It should be as well thought out as possible.

1. Buying a better header connector (something with a shorter profile, since the current header presses against the lid when connected to the effects PCB). Also looking for a latching set. Another option is those "PCB" headers, where you etch pads onto the side of the PCB and carve out a little notch on each side, and the header slips onto the side of the PCB.... More space efficient, maybe less reliable...
2. I got a few strips of SMD components and SMD op amps, I might have a go with trying out SMD for the base board, since the SMD components can be mounted underneath the input/output jacks!
3. Maybe adding a 5v regulator to the base board for digital chip uses

The tap tempo input was an idea I was considering. Like I believe I said earlier, I was going to make a larger base unit with two switches. The unit would use electronic switching with momentaries. This will allow the footswitch controls to be utilized as either tap tempo switches or bypass switches, depending on the position of a DIP switch on the internal PCB. The footswitch LED's would change color according to their current mode, and they will turn on/off in accordance with the mom/latching style they are set for. The smaller version will be like the one I made, true bypass, likely external tap input.

I'm sticking to the potentiometer plans. I still think that having the pots directly mounted on the effect will make the whole process much easier. Pots are so expensive that I would be worried about conserving them...


Basically I think the header will end up having pins designated

Effect Input
Effect Output
Tap Input
V+
V-
5VDC
1/2V+

If you think of anything else please suggest it 

[Quackzed]

for tap tempo, you could have a dedicated jack (maybee 1/8" mono) on the base unit, and build a single tap tempo switch box with a 1/8" jack and just plug it in for effects that utilize the extra 'tap tempo pins' on the connector.

[rnfr]

wow. both of those designs look way more useful and elegant than that over-complicated inventothingie.  nice job guys!

[MoltenVoltage]

Actually, use a stereo jack for the tap tempo and you could run two separate switches off a single stereo cable.

Or it could be used as an LFO input if you wanted to make a central LFO unit for your board, like in this video:
http://www.moltenvoltage.com/mv-53.html

The LFO unit connects into the other unit with a 1/4" cable and runs three different effects, each of which has a buffer on the LFO input.  Its a nice way to sync up all your LFO-based effects.

Just put all three connections on the header for the main switch PCB.

[JKowalski]

for tap tempo, you could have a dedicated jack (maybee 1/8" mono) on the base unit, and build a single tap tempo switch box with a 1/8" jack and just plug it in for effects that utilize the extra 'tap tempo pins' on the connector.

Thats exactly what I was going to do. If you look at my tap tempo trem I made a while ago I have a bank of 1/8" connectors for tap tempo interfacing among all my modulated pedals. This would follow the same convention.

I'm almost done with the tap control box, I have the hardware/software designed and ready but I need to pick up an quad XOR gate (the controller outputs through 8 jacks. They are arranged in banks of two, and any bank can be made to output either pulse or clock (set in the software), and invertable (set by dip switch and XOR gate).

Actually, use a stereo jack for the tap tempo and you could run two separate switches off a single stereo cable.

Or it could be used as an LFO input if you wanted to make a central LFO unit for your board, like in this video:
http://www.moltenvoltage.com/mv-53.html

The LFO unit connects into the other unit with a 1/4" cable and runs three different effects, each of which has a buffer on the LFO input.  Its a nice way to sync up all your LFO-based effects.

Just put all three connections on the header for the main switch PCB.

My board is set up so that all my modulated pedals utilize Electric Druid's TAPLFO chip, and they all carry a tap tempo clock output and input, so they are all synch-able. Plus, each pedal can be synced to each other but use different timing intervals (1/2, 1, 2, etc.) and a different wave, since the interconnection is just a base time instead of an actual LFO.

[Quackzed]

 
great mind think alike, right?
i really like the idea of a master lfo/clock that keeps everything in sync , and allows you seperately sync each pedal to double or half etc.. the rate,AND is adaptable to any modulated effect ...
its not obvious, but it seems like syncronization is a  byproduct of making a modular lfo.
or at least an lfo that is feeding more than one effect.
     but if your doing an lfo tap tempo,
what about a volume pedal controller you can plug in (1/8")and have control of one pot from each effect...rate for chorus, wet level for delay, gain amount, or even clipping threshold for diodes...etc.
even if it was utilized by only a few select pedals, it would be interesting to design something around the ability to have some level of foot control. where it is impractical to have a volume pedal attached to every fuzz you build, it suddenly isn't verry difficult to imagine a dedicated volume pedal jack to the connector to any effect that wants to use those pins

[JKowalski]

what about a volume pedal controller you can plug in (1/8")and have control of one pot from each effect...rate for chorus, wet level for delay, gain amount, or even clipping threshold for diodes...etc.
even if it was utilized by only a few select pedals, it would be interesting to design something around the ability to have some level of foot control. where it is impractical to have a volume pedal attached to every fuzz you build, it suddenly isn't verry difficult to imagine a dedicated volume pedal jack to the connector to any effect that wants to use those pins

Ah, but now you are starting to make a modular synthesizer 

I'm not going to go that far, especially for this "base unit". It's not really meant to (well, my take on it) do complex circuits, it's more focused on the various tiny circuits that I feel would be useful in some situations but not worth the money to place it into a nice, dedicated box. I haven't found anything that I absolutely need foot controlled on any of my "dedicated" effects, but I suppose when I did I would design for that specifically.

Remember, the "expression pedal" is a system already in place on many commercial effects. I'm not sure... is that just a rheostat with either end connected to a stereo jack? I've never had the opportunity to look into one. Regardless, designing for those would be the obvious solution.

[soggybag]

Hey that's pretty nifty, great idea. Cheaper than an Invento Box!

Looks like you could build a lot of stuff on that. You have it set up to use a PS. What if you moved the switch to the left or right, you could put a battery clip in there and run it off a 9V.

Looks like the switch overlaps the two breadboards a little?

[JKowalski]

Finally got around to remaking stompbox base unit, with two modules: a BMP and a Rebote Delay. Also finally found a use for the handful of SMD parts I have lying around.



Fixed all the problems I had in the prototype. Though in hindsight, it would have been alot easier to use a larger box for this. 

[soggybag]

Great idea, that looks great.

[amptramp]

Just out of curiosity, do you know what alloy of aluminum you are using for the etched plate?  If you are using 2024, it should etch much more quickly than 6061 which is the other common high-strength alloy.  What thickness are you using for it?

[JKowalski]

Great idea, that looks great.

Thanks

Just out of curiosity, do you know what alloy of aluminum you are using for the etched plate?  If you are using 2024, it should etch much more quickly than 6061 which is the other common high-strength alloy.  What thickness are you using for it?

No idea whatsoever. I had some scrap pieces lying around that I've been cutting up and using over time. They are both about the thickness of my driver's license

Actually, the two plates you see are from different scrap pieces. In real life you can see that the eagle design plate is a little shinier and bluish while the doctor who plate is a little more matte and greyscale. The second one etched ridiculously fast - so fast that the toner started melting from the intense heat of the reaction and ruining the etch even when using used ferric chloride (with enclosures its not so bad, it acts as a heat sink... but these are so small. I had to do a couple tries....) The eagle design plate, while about the same thickness, is sturdier then the who plate and etches a little slower.

[puretube]

Looks more useful that the inventobox already!!
Nice work.

John

Oh, really?

[bassk81976]

this is a nice idea! I had a similar one, but i was gonna thing to wire up a multi-fx box that can be added to as i go, not sure how to though.. so if i really like the effect i can put it in it's own box, otherwise i add it into the multi-fx enclosure. Needs some thinking, though...

[BRingoC]

Wow, that is great.  Seems like it makes so much sense that it would be impossible to not make money off of this idea.  This is definitely one of those 'wish I had thought of it' things.

[mattthegamer463]

My only thought on that thing is that you can only use pedals which actually use those 3 specific pot values.  If you want more pots or different values and curves, you're pretty much SOL.  Any workaround on that?

[Quackzed]

My only thought on that thing is that you can only use pedals which actually use those 3 specific pot values.

If you're talking about the 'base unit' , the pots are part of the circuit board, and come out of the 'base unit' along with the circuit. It uses the pot shafts to mount the circuit, so they are a permanent part of the modular circuit board, not the 'base unit itself.
so if you want a different effect with different value pots, you'd just put different value pots on the circuit board of your new circuit, but in the same spots, so you can 'fit' it into the base unit. so its covered.