MXR Micro Amp MOD: TB + MOMENTARY (T.C. Spark Mini Style)

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MXR Micro Amp MOD: TB + MOMENTARY (T.C. Spark Mini Style)

Postby JDB » 19 Feb 2019, 17:49

Hey Everyone! First post here! My apologies if I've posted this in the wrong forum, wasn't sure if here or the how-to section would be the proper place, but I figured the Micro Amp is pretty cheap...

So, Can I mod the same style switch as the T.C. Electronics Spark Mini into an MXR Microamp? (LATCHING On-Off + MOMENTARY option in the SAME switch)

I’ve read before in the past that a True Bypass, Latching On-Off 3PDT + Momentary in the SAME switch didn’t exist.
But the T.C. has this function, so is there now more recently a switch like this available?
Even if it’s the “Soft Click-less Style Switch” like the Spark Mini - that would work just fine.

If not, we’ll do it anyway! I’ve read that modding the Microamp to True Bypass alone can be quite tricky and somewhat dangerous for an amateur. So instead would order this: https://store.generalguitargadgets.com/ ... e-kit.html
A Microamp Clone kit, (which thankfully is on a much smaller PCB than the MXR) allowing enough room to add a second Momentary switch (if needed) and still have room for the battery in a new custom drilled 1590B enclosure.

Question:
If this is the only option (Build the Microamp clone with 1 Latching + 1 Momentary switch)
What type of Momentary Switch am I looking for? I know you need the 3PDT for True Bypass, but I can’t find a Momentary 3PDT. Is there such thing? Or do I just need a common DPDT? Or would even a SPST work?

Wiring diagram of the Micro Amp clone kit: http://www.generalguitargadgets.com/pdf/ggg_mamp_lo.pdf

Would someone kindly be able to show a wiring diagram like this of how to properly wire in a Second Momentary switch in parallel?
***Note, The 9VDC power supply is NEVER used. Can the entire power supply jack be omitted from the diagram for a Battery Use only wiring setup? That’d be great if possible.

Or would it be easier, or is it possible to just buy the Spark Mini and take whatever switch they have outta there and wire it into the Micro Amp? Sorry if that’s a noobish question, just started the DIY fun recently, still learning here…

Thank you all very kindly for any help you may be able to offer!

-Jonny
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Re: MXR Micro Amp MOD: TB + MOMENTARY (T.C. Spark Mini Style

Postby plush » 19 Feb 2019, 20:11

Hi,

So, if you want your pedal to respond to the switch in similar fashion to TC Spark Mini, you should be looking not for a particular momentary/latching switch, but for a microcontroller (attiny or pic or any other one) and especially it's firmware, that can control a relay and handle all the switching. Learn to code, everything left is pretty minor.
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Re: MXR Micro Amp MOD: TB + MOMENTARY (T.C. Spark Mini Style

Postby JDB » 20 Feb 2019, 01:29

Hi Plush, thanks for your reply!

Forgive me, I'm new to all of this and even newer to micro-controllers and relay switching!
In researching your advise I found these two relay modules.

https://www.mammothelectronics.com/prod ... module-kit

https://buildyourownclone.com/products/ ... pass-board

The Mammoth install guide seems reasonable enough to pull off.
But my question is with the switch:
Would the switch that comes with the Mammoth be the dual function Latching On-Off + Momentary option when required?

The BYOC relay bypass comes with the option of either a DPDT or SPST Momentary switch. Would either of those pull off the function I'm looking for?

Or have I missed the boat completely, and are these options just Momentary only switches that would have to be wired and used in conjunction with a Latching TB switch?

Thanks so much for your help!
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Re: MXR Micro Amp MOD: TB + MOMENTARY (T.C. Spark Mini Style

Postby plush » 20 Feb 2019, 15:36

JDB wrote:Hi Plush, thanks for your reply!

Forgive me, I'm new to all of this and even newer to micro-controllers and relay switching!
In researching your advise I found these two relay modules.

https://www.mammothelectronics.com/prod ... module-kit

https://buildyourownclone.com/products/ ... pass-board


Both are unreasonably pricy.
You can make one for yourself for 5-8$

JDB wrote:The Mammoth install guide seems reasonable enough to pull off.
But my question is with the switch:
Would the switch that comes with the Mammoth be the dual function Latching On-Off + Momentary option when required?


Relay's switching mechanic is defined by the microcontroller's firmware. The button that provides input signal is usually momentary (non-latching).
I can't see any statements on Mammoth MCU functioning other than latching.

JDB wrote:The BYOC relay bypass comes with the option of either a DPDT or SPST Momentary switch. Would either of those pull off the function I'm looking for?


Can't see said option, but a lof of bullshit from BYOC.

JDB wrote:Or have I missed the boat completely, and are these options just Momentary only switches that would have to be wired and used in conjunction with a Latching TB switch?

Thanks so much for your help!


Yeah, it seems so.


Oh hell, i hate this but...

Let me explain how this thing works. Expect lots of flaws and mistakes.

The diagram looks loke this:
[Foorswitch]--->[MCU]--->[RELAY]+[LED INDICATOR]

Footswithc is pressed by our meaty parts.
MCU follows certain instructions/algorythms.
Relay switches between contact groups.
LED indicates.

So, we have an input pin on the MCU (lets call it PIN-A), that defines what is happening. The PIN-A is set to be "digital" that means it can either be 1 or 0.
"1" means that pin is pulled up to a certain voltage close to MCU's VCC (e.g. 3.3-5v)
"0" means that pis is at ground level

So you take a resistor (usually 10k-100k), connect it between PIN-A and VCC and PIN-A becomes lifted by default (1)
Then you add a switch between PIN-A and gnd that, when pressed, it effectively pulls the PIN-A down to ground (0), said switch is usually non-latching (momentary), with normally open (not connected) contacts.

MCU is programmed to sense PIN-A state and react respectively.

Let's say, there are 2 modes of the MCU and 2 algorythms, that define what is happening when the switch is pressed.
Mode 1: Latching mode
Mode 2: Momentary mode
Sub algorythm: Changes between Mode 1 and Mode 2
Algorythm 1: Controlling relay and LED when Latching mode is active
Algorythm 2: Controlling relay and LED when Momentary mode is active

So, you set all your free pins to do stuff, then you organize intput pin (PIN-A) monitoring.
First we need to define how everything should work - define switching algorythm.

We apply power, MCU is booted.

Mode 1 (latching) is set by default.
Relay is OFF, LED is OFF.

Let's assume it takes us 10ms to press and release the switch.
We add counter to PIN-A, that begins counting when PIN-A's state changes from 1 to 0.

We press footswitch, PIN-A is 0.

Algorythm 1 starts

The counter starts counting. Once it counts to 10ms, it tells us to switch relay ON and LED ON.
Relay and LED stay ON.

The counter is still counting.
Then there are 2 options (sub algorythm):
1. We release the switch. Counter is zeroed and stops working. Mode 1 is still present.
2. We hold the switch untill the counter counts up to certain time (lets say 5000ms = 5 seconds). Then, it decides that we are holding the switch for so long cause we want it to change operating mode, so it changes Mode 1 to Mode 2. Counter is zeroed and stops working. We can proceed to hold the switch for no reason or release it.

Algorythm 1 ends

If Mode = 1, then pressing the switch again causes the MCU to switch pedal OFF and LED OFF. And everything happens again.
---

But, if we chose option 2 and the Mode is 2 (non-latching), then:

We then need to turn the pedal (press the switch) off to make Mode 2 work.

Relay is OFF, LED is OFF.

We press footswitch, PIN-A is 0.

Algorythm 2 starts

The counter starts counting.
Relay is turned ON, LED is turned ON

The counter is still counting.

Then there are 2 options (sub algorythm):
1. We release the switch. Counter is zeroed and stops working. Mode 2 is still present. Pedal is OFF, LED is OFF.
2. We hold the switch untill the counter counts up to certain time (lets say 5000ms = 5 seconds). Then, it decides that we are holding the switch for so long cause we want it to change operating mode, so it changes Mode 2 to Mode 1. Counter is zeroed and stops working. We can proceed to hold the switch for no reason or release it. Pedal is ON, LED is ON

Algorythm 2 ends

And so on. Kill me pls.
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Re: MXR Micro Amp MOD: TB + MOMENTARY (T.C. Spark Mini Style

Postby Feral Feline » 16 Mar 2019, 00:06

I'm not savvy enough with programming etc... I'd just add a DPDT momentary switch that can bypass a 3PDT latching bypass.

2PDT MOMENTARY
LUG 1> BOARD INPUT
JACK > LUG 2
LUG 3> 3PDT MASTER BYPASS IN


BOARD OUTPUT > LUG 4
LUG 5 > JACK
3PDT MASTER BYPASS OUT > LUG 6

Somebody with more experience could probably come up with a better way to route the signal.


For shigs and gittles...
Have a look at this momentary switching schematic from https://0xdfx.wordpress.com

Image

That may give you an idea on a way to add a momentary switch to your Micro Amp so it could be an always on and then momentarily bypass it for weird tremolo effects etc.
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