madbeanpedals::forum

Projects => Tech Help - Etcher's Paradise => Topic started by: zoof on December 11, 2017, 04:48:02 PM

Title: Holy Roller - Verified
Post by: zoof on December 11, 2017, 04:48:02 PM
Works like a charm! Got best result with 1m dark ldr and 5mm red diffused.
Title: Re: Holy Roller - Verified
Post by: madbean on December 11, 2017, 05:51:31 PM
Great news! What's it like?
Title: Re: Holy Roller - Verified
Post by: zoof on December 12, 2017, 10:52:52 AM
I love it. Built it on vero a couple of weeks ago, this is a little more fun to put in a box though!
Don't know how to describe it, it's there, but not harsh. It does the job it says it will do, it's a limiter :)
Really recommend this.
Title: Re: Holy Roller - Verified
Post by: jubal81 on December 12, 2017, 11:04:59 AM
Seeing a couple points on this schematic that could possibly cause noise issues. Find it any noisier than other compressors?
Title: Re: Holy Roller - Verified
Post by: zoof on December 12, 2017, 11:31:34 AM
Quite the opposite, didn't notice any noise at all. Haven't played it loud yet though.
Title: Re: Holy Roller - Verified
Post by: chordball on December 12, 2017, 01:09:39 PM
Seeing a couple points on this schematic that could possibly cause noise issues. Find it any noisier than other compressors?

Can you elaborate? Any ideas for improvements? I haven't built it but it was on my radar.
Title: Re: Holy Roller - Verified
Post by: jubal81 on December 12, 2017, 01:37:22 PM
Seeing a couple points on this schematic that could possibly cause noise issues. Find it any noisier than other compressors?

Can you elaborate? Any ideas for improvements? I haven't built it but it was on my radar.

Mainly thinking about the LDR on the noninverting opamp input going to a reference voltage. Noninverting inputs have ridiculously high impedance, so that net is extremely sensitive to picking up noise. It's a good idea on layout to keep any traces connecting to a noninverting input absolutely as short as possible.

I've noticed that phasers that use a negative voltage for a split supply rail are much quieter than those with a single rail and reference voltage. If you look at the Mutron Phaser schematic, you see the noninverting inputs and corresponding LDRs are referenced to ground in the phase stages.

Title: Re: Holy Roller - Verified
Post by: chordball on December 15, 2017, 02:08:32 PM
Seeing a couple points on this schematic that could possibly cause noise issues. Find it any noisier than other compressors?

Can you elaborate? Any ideas for improvements? I haven't built it but it was on my radar.

Mainly thinking about the LDR on the noninverting opamp input going to a reference voltage. Noninverting inputs have ridiculously high impedance, so that net is extremely sensitive to picking up noise. It's a good idea on layout to keep any traces connecting to a noninverting input absolutely as short as possible.

I've noticed that phasers that use a negative voltage for a split supply rail are much quieter than those with a single rail and reference voltage. If you look at the Mutron Phaser schematic, you see the noninverting inputs and corresponding LDRs are referenced to ground in the phase stages.

Thanks for the explanation. Definitely not something I even considered before so I learned something new. If/when I build this circuit I will play around with the supply scheme.
Title: Re: Holy Roller - Verified
Post by: gordo on December 15, 2017, 08:32:54 PM
This one has been on the radar for a long time so might have to bust out the FeCl if I can find the pcb's (house is packed up and ready to sell).
Title: Re: Holy Roller - Verified
Post by: Masochist on May 16, 2019, 11:48:22 PM
Works like a charm! Got best result with 1m dark ldr and 5mm red diffused.
I know this thread is kind of old but I'm going to be building one of these pretty soon so I just wanted to ask if you mean any LDR with a min 1mOhm dark rating? Sorry I'm pretty new to electronics but keen to learn!
Title: Re: Holy Roller - Verified
Post by: Aristatertotle on May 17, 2019, 06:08:38 AM
Works like a charm! Got best result with 1m dark ldr and 5mm red diffused.
I know this thread is kind of old but I'm going to be building one of these pretty soon so I just wanted to ask if you mean any LDR with a min 1mOhm dark rating? Sorry I'm pretty new to electronics but keen to learn!

Probably means something 1 Meg dark, lower resistance light.
http://smallbear-electronics.mybigcommerce.com/photocells-cds-5mm-diameter/ (http://smallbear-electronics.mybigcommerce.com/photocells-cds-5mm-diameter/) like the 8005 option of these.
Title: Re: Holy Roller - Verified
Post by: Masochist on May 21, 2019, 10:34:06 PM
Thanks mate :)
Title: Re: Holy Roller - Verified
Post by: Masochist on June 07, 2019, 01:54:04 AM
Sorry to hijack this thread again but could someone please illuminate me as to what the 'L' pad is for? It's by itself to the right of the LED +/-.
Title: Re: Holy Roller - Verified
Post by: somnif on June 07, 2019, 02:27:15 AM
Sorry to hijack this thread again but could someone please illuminate me as to what the 'L' pad is for? It's by itself to the right of the LED +/-.

Its the "switch" pad for the LED, equivalent to the Grey wire (coming off the LED) in the latter examples in this pdf: http://www.madbeanpedals.com/tutorials/downloads/MBP_FootswitchWiring.pdf

It is the ground path for the LED. When the pedal is "off", the LED is un-grounded, so it doesn't glow. When the pedal is "on", the L pad is switched to ground, so current can flow through the LED and it lights up.
Title: Re: Holy Roller - Verified
Post by: Masochist on June 10, 2019, 07:37:09 AM
Oh ok.. so do I connect the LED + and -, and the L goes to the 3PDT like in the document you linked? Sorry I haven't built a pedal with this kind of configuration before! Plus even though I've built a bunch of pedals I am still a bit of a noob when it comes to electronics! Appreciate your help!!