Belcat 303 delay pedal

phantompowers · June 21, 2010, 01:22:48 PM

Sorry it's a bit blurred, my camera's been drinking.

This is a really lame pedal in its unbent state but has the capabilities for being a lot more powerful. It also comes in a sturdy metal case which is cool at this price level.

The above modification, right leg of the 'rate' pot to pin 6 of the chip, will reduce the delay time drastically to a really short delay, giving an almost plate reverb effect. I also changed the pot to a 500k to extend the delay time. With a 500k pot, the delay time is extended to about 6 seconds when it is fully on. However, the delay is really muffled and distorted at that level.

I did also manage to get a feedback loop but my notes are so messy I can't figure out how I did it. I will update this post next time I take the back off.

I also fitted an LFO circuit to control the vibrato, after being inspired by a circuit bent fab echo on this page - http://circuit-bent.net/modified-fab-echo.html

This was done by making a 555 timer circuit, then attaching it to the legs of the 'rate' pot via a vactrol. This creates some really interesting effects.

How to increase the delay volume managed to elude me but hear is a picture of the other side of the board, so hopefully Gordon can point me in the right direction!!

Gordonjcp · June 21, 2010, 07:29:41 PM

Grab the datasheet for the PT2399 chip and have a read, I'm sure you'll figure out how to increase the echo level.

You'll want a decent pair of tweezers and a fairly pointy soldering iron to do the SMD rework. Solder braid works well for desoldering them - get the stuff about 1mm wide, and use plenty of heat.

phantompowers · June 22, 2010, 09:05:53 PM

Damn those tiny SMD's!

Gordonjcp · June 22, 2010, 09:20:07 PM

Those are *huge* SMDs. Massive. I'd use my ordinary soldering-PL259-connectors iron on those.

Tomorrow I'll get you a pic of tiny SMDs.

phantompowers · June 23, 2010, 10:18:40 AM

Surely you jest?

Gordonjcp · June 23, 2010, 02:06:23 PM

http://www.gjcp.net/~gordonjcp/capacitor.jpg

DC blocking cap on the microphone input of an Icom IC-F15S radio. The pointy thing is a perfectly ordinary Swann-Morton scalpel blade. The SMD cap is about 0.5mm by 1.5mm and isn't the smallest part on the board. They are easily damaged when resoldering the accessory socket, so you need to be careful in there...

jamiewoody · June 23, 2010, 04:58:07 PM

who makes these belcat pedals anyway? as i understand they are made in china (be sure not to lick your fingers, you might eat lead! lol!). i have seen this same style of pedal with other names screened on the box...

they are NICE stomp boxes for your money! i had a chorus once, and it reminded me of something very early 80s, very analog, very thick and syrupy! not quite an mxr, but almost!

jamiewoody · June 23, 2010, 05:09:08 PM

what if you were to connect ANOTHER 500k pot between the rate pot and pin 6 of the ic? i know, that would require drilling, and finding a place for it...but, might be cool?

phantompowers · June 23, 2010, 06:41:48 PM

Haha, that really is small. I wouldn't dare go near one of them!

I'm still not having much luck with changing the echo level. I downloaded the datasheet for the PT2399 but I still don't understand what all the pins are for, OP 1 IN, OP 2 OUT etc. I'm slowly getting there though!

Jamie - adding another 500k pot would just increase the overall resistance to 1M, something which could be achieved by just using a 1M pot.