DOD fx15 swell pedal

[El Heisenberg]

http://www.diystompboxes.com/smfforum/index.php?topic=76457.40


http://www.dirk-hendrik.com/temp/dod_fx15.pdf



I want this in the same box as a slow gear I've perfed up.

Last nite I finally got to breadboard it and it didn't work. I had to change the 4.7uf cap to 10uf, and the LDRs, 10k resistor to 680 ohms!

I used a LDR/green LED combo so I figured it might work different.

The cut/boost control isn't really usefull to me. It's almost like the volume sits a little lower and when the boost control is up it tries to do the opposite of volume swell. Which would be cool if it worked.

Dont have a 500k C taper pot for the attack, so I used a 500k linear, but it sounds like it just does what the decay control does. So I could just leave out the cut/boost and attack pots and use fixed resistors. The 100k decay control works great and I love the way this thing works.

Weird too, T2s emitter has a weird 10k/5k trimmer thing to ground and Vcc. I don't get this. didn't have a 5k or 10k trimmer on hand anyway so I just left the emitter to ground. I tried using a 5k pot to adjust this, but like I thought, it didn't do anything good.


What's with this pedal? Schematic have errors? The other folks who've buit this, like solderman couldn't have used the orignal vactrol could they?

[Mugshot]

necrobump!

I used a LDR/green LED combo so I figured it might work different.

on mine, the LDR pops during initial attack, particularly during quick attacks.

I used a LDR/green LED combo so I figured it might work different.

i used a super bright white one. green LEDs i have tried wont light up well.

The cut/boost control isn't really usefull to me. It's almost like the volume sits a little lower and when the boost control is up it tries to do the opposite of volume swell. Which would be cool if it worked.

...and possible phasing issues? i ditched the cut/boost control last night on breadboard and hard-wired the LDR and cap parallel to the 1M feedback resistor. i think a better control would be a 500K pot in series to a 470K fixed resistor that will replace the 1M resistor connected between the 2 opamps.

Dont have a 500k C taper pot for the attack, so I used a 500k linear, but it sounds like it just does what the decay control does. So I could just leave out the cut/boost and attack pots and use fixed resistors. The 100k decay control works great and I love the way this thing works.

i tried ditching the 100K and used instead a 500K with the center terminal connected to the 4.7uF cap and the outer lugs connected to the transistor collectors. i cant remember whether i liked it or not, but i think having the 100K+500K pot combo gives better attack response.

Weird too, T2s emitter has a weird 10k/5k trimmer thing to ground and Vcc. I don't get this. didn't have a 5k or 10k trimmer on hand anyway so I just left the emitter to ground. I tried using a 5k pot to adjust this, but like I thought, it didn't do anything good.

this part weirds me out, too. VCC>10K to emitter? what gives? i took out the VCC and 10K and used a 3K trimmer instead but thought tying the emitter to ground didnt make a difference. but the transistor voltages are off, i think: the base is higher than the collector; adjusting the emitter resistance to ground lowers/raises the collector-base voltage as well.

the only problem i have had last night breadboarding this thing is the LDR popping when the LED is at its brightest and sudden turn on.

another question: why not make the 1st stage inverting?