Original effects with schematics, layouts and instructions, freely contributed by members or found in publications. Cannot be used for commercial purposes without the consent of the owners of the copyright.
mirtzbass wrote:hi! one question : can i use this system with a boss ds-1?? thanks
You can use it with any pedal that needs "true bypass".
Two things to remember - the relay MUST be the right type: TAKAMISAWA AL5WN-K and the switch MUST be a LATCHING type (unless you're going to drive it with logic).
"Why is it humming?" "Because it doesn't know the words!"
mirtzbass wrote:hi! one question : can i use this system with a boss ds-1?? thanks
You can use it with any pedal that needs "true bypass".
Two things to remember - the relay MUST be the right type: TAKAMISAWA AL5WN-K and the switch MUST be a LATCHING type (unless you're going to drive it with logic).
many thanks man!!! if i have time i will make a pcb
Unfortunately, neither of these are BISTABLE LATCHING relays. A bistable relay has a mechanical locking mechanism that holds it in either the set or reset position even when the power is removed. That's why the switching circuit uses so little power - when you close the switch, the relay draws a little current as the capacitor charges and the contacts change over. While the switch remains closed, there is only a minute current passed through the high value resistor. When the switch is opened, the capacitor is discharged, the relay changes back, and obviously there's no current drawn from the battery because it's disconnected!
You can get the genuine Takamisawa AL5WN-K from many ebay sellers (that's where I get mine). I buy them by the hundred!
"Why is it humming?" "Because it doesn't know the words!"
What type of stomp switch do you use? Seems you still need a switch. The switching system might have some advantages but, I can't see price as a being a big factor. The blue 3PDT type switches are very cheap.
soggybag wrote:What type of stomp switch do you use? Seems you still need a switch. The switching system might have some advantages but, I can't see price as a being a big factor. The blue 3PDT type switches are very cheap.
Originally, I came up with this use of the relays so that I could use up all the SPDT switches that I'd removed over the years when converting pedals to "true bypass". I had a drawer full of them!
Nowadays, there are very good quality single pole push switches available for much less than the nasty TPDT footswitches. I use "vandal proof" stainless steel push buttons that are designed for outdoor use. The ones I use are latching ones, but momentary ones are available for use with CMOS logic. The switches are seemingly indestructible and completely waterproof!
"Why is it humming?" "Because it doesn't know the words!"
Cub wrote:Get on this, lads. Proper loads of AL5WN-K relays !
I buy them in 50s!
All right, you win ! I ordered enough to let the TriAxis and G-Major switch things in my rack and some more in case I mess up or want to mess about with them some more in the future.
I wish I were a chestnut tree, nourished by the sun.
With twigs and leaves and branches and conkers by the ton.
Thanks a lot for this circuit. I've installed it in my wah, using a slightly modified version of the layout on page 3, 2n3904/2n3906 and the original Carling SPDT. I didn't check the transistor pinout, and just copied the transistor outlines from the layout, and it didn't work at first, but I soon figured out that although the bce labels on the layout are correct, the outlines on the layout are the wrong way round (I hope this helps somebody!). I have also wired the switching contacts differently from the layout, to ground the input in bypass mode using what I think is a fairly standard scheme.
It works very well, except I am having a problem with a loud popping when the wah is switched on. Switching to bypass mode is silent. Using a Taiwan 3PDT wired in exactly the same way (as a DPDT) I have no popping at all through the amp. Not grounding the input in bypass mode makes no difference. A 2.2M resistor between fx input and ground makes no difference either - a resistor shouldn't be necessary on the output as it is referenced to ground through the pot.
So at this point I'm wondering what is causing the popping - it doesn't seem to be anything to do with the input or output caps building up a charge, as anti-popping resistors make no difference whatsoever, and it works just fine with a normal switch. It isn't the LED (there isn't one!). Could it be the magnetic field from the relay being picked up by the inductor (they're about 3 inches apart)? If so, how to cure it?
I'd really like to use this system as the Carling SPDT has a much nicer feel than the 3PDT in a wah, as it has a shorter travel before engaging and is mechanically quieter, but I'm scratching my head at the moment!
It might be the momentary change in current drawn when the relay engages (there's a small spike on the +9V line). Supply filtering is the answer here - put (perhaps) 100R in series with the +9V supply to the wah board, and put (say) 220µF at 16V across the wah PCB from +9V to ground. This should eliminate your switch-on pop.
"Why is it humming?" "Because it doesn't know the words!"
I couldn't think of an easy way to implement the supply filtering on my existing board - I will probably install a dc jack just so I can hard wire the filtering components to it - but I tried connecting the relay board and switch to a separate battery to see if this was indeed the cause of the popping.
Well, it has cured the popping when the wah is switched on very effectively, so I guess adding some supply filtering should work too! However I am getting some popping through the speaker on switch off now. I suspect this may have been happening all along and I just didn't notice it because the switch on pop was so much louder. Anyway, it would be nice to get rid of this too, but it is much better now, so thanks for the advice!
mictester wrote:
Nowadays, there are very good quality single pole push switches available for much less than the nasty TPDT footswitches. I use "vandal proof" stainless steel push buttons that are designed for outdoor use. The ones I use are latching ones, but momentary ones are available for use with CMOS logic. The switches are seemingly indestructible and completely waterproof!
What kind of V-R swithces are suitable? Seems like all the ones i've seen dont look like would be easily operated as a "foot" switch
![[smilie=a_biggrin.gif]](./images/smilies/a_biggrin.gif "a_biggrin"){kind=small}
I ordered enough to let the TriAxis and G-Major switch things in my rack and some more in case I mess up or want to mess about with them some more in the future.
