zvex lofi loop junky - hows that work?

[gurutzeta]

the biggest problem with winbond is that they changed their control circuitry so many times that it makes your head spin when you try to come up with circuits to make them into effective loopers.  the one i use, the 1420, can be replaced with another in the 1400 series that is slightly shorter but has higher frequency response, and i've never liked a thing about it.

I seem to remember reading in the datasheet that the new chips (ISD25...) control circuitry is somehow compatible with the old chips (ISD14...).

[zachary vex]

Eeeek.  :shock: Well, I ordered a 2560 for my Gurutzeta box.. I hope it will work ok.

60 should be OK is from there onwards that starts getting bad. Basically the 120 is the same chip as the 60 but with a sample frequency of half of the one in the 60.

Bellow 60 the chips are the same as the 60 (sample frequency wise) but with less capacity, less "analog memory"

man, that sucks!  i never researched those really big chips, because it was impossible for me to make everything fit in a small form factor.

[gurutzeta]

On reply to some questions sent to me on private messages:

Sw10 in the pcb (over c16) should go to the pole of one of the circuits of the DPDT switch used for the safe switch

SW12 is connected to SW20 and should go to one of the throws of SW10

Code Select Expand


Safe DPDT Switch

open---o o---5 Volts
sw10---o o----(470 ohm resistor)---( LED )---Ground
sw12---o o---Ground




sw20 is connected to the pole of the Play/Rec Stompswitch

Code Select Expand



PLAY/REC Stompswitch

N.C.---o o---5 Volts
N.C.---o o---SW20
N.C.---o o---Ground



sw22b and sw20b  should be connected together in the PCB. I used to have them connected to the Play/record stompswitch but it made a horrible pop at the end of a loop, so just connect them together.

About the two color LED, it should be one with only two connections coming out of it, not the one with three connections. There are 2 types of bicolour LEDs, with 2 or with 3 leads. You need the one with 2 leads: 228-5641 in RS components in the UK.

Remember to put a 1Meg resistor between inFX and Ground, I forgot to put it in the PCB.

Last... T1 is a mosfet so there are no E, B or C pins on it, instead it has S, G, D. D is connected to LED2, G in the middle and the other one is S

[ethrbunny]

Grand. Back to the garage.

This build has me psyched out somehow. I can't seem to get a handle on finishing it. Silly.  :roll:

[ethrbunny]

oooookay.. so I finished this build today. (freezing rain is falling outside - my kids are going nuts.. so naturally i retreated to the garage. It may be only 20 degrees in there but its *quiet*)

The circuit *works* with a few minor issues:

1) led2 won't light up. Im using a BS170 for the FET.
2) turning the pot for playback volume gives me a radio station on one end and doesn't really bring the playback volume to anything near a usable level
3) Theres a background hum that overpowers the playback (in addition to #2 above)

On the 'analog' page you have the FX loop with a 'jack switch'. Can you tell me what this is? I put a DPDT switch on mine but I notice from your pictures that you only have 2 stomp switches and 1 toggle.

Ill start poking at electrolytics and looking for solder bridges.

[Sic]

So i tried throwing together the Dean Hazelwanter Version (there wasn't a full schematic, just the op-amp layout) and so far i have recording, and looping... but it is REALLY splatty... it sounds like the guitar is  WAAAAAAAY overdriven almost to a point where you can not understand what is going on. Also i seem to have a large volume drop playing straight through it... when in bypass its loud, then when i play through the op-amps and the chips... i get WAAAY less volume.

I'm using the ids1420 and 2 TL072's.

also i didn't include the record volume, just left it with a .01uf cap straight into the ana in


the op-amp schematic im using is Loopy

comparing what i have to the PCB layout, i don't have the 4001 ic...


i have a good start i think, but a long ways to go... hehe... i wish the GGG version had a little more documentation along with it, but beggars can't be choosers.

Thanks ahead of time

[Sic]

man, i've been staring at this all day, and i don't have a clue what needs to happen to get this working like i want it to

[Dean Hazelwanter]

Both schematcs (digital and analog sections) are here: http://generalguitargadgets.com/index.php?option=content&task=view&id=203&Itemid=228, as well as the board layouts. For some reason (likely time constraints) JD didn't include the (brief) build notes I sent, so here they are:

Release Notes:

General
- Inspired by VZex's LoFi Loop Junkie and
- Based on 20 second voice recorder chip, Winbond ISD1000A - Why, because I had one. Although they are obsolete, some RadioShack stores still have them (276-1325) in their discount bins.
- Three pots: Record Level (to optimize the signal level going into the ISD1000A), as well as Playback Level and Dry Level.
- Two footswitches : Record/Play (lights red 'Record' LED in record position), and On/Off (lights green 'On' LED in on position). 'Record/Safe' switch (toggle or slide) helps to prevent over-writing saved loop

PCB
- There is a long vertical jumper near the middle of the board, which carries the signal into the ISD1000A. Notice that there is an extra, grounded, pad to the right of the bottom of this jumper. When I laid out the PCB, I put this ground pad in case the long jumper picked up noise, so the jumper could be shielded. It doesn’t seem to be a problem, so the jumper doesn’t need to be shielded.
- All of the off-board wiring is laid out to use 3 pin 0.1" center connecters that I've been using for a while. One connector for the 2 switches, one for the 2 LEDs, one for each of the 3 pots, one for each of input and output jacks, and one for 9v DC.
- The corners of the PCB can be notched out to mount it in a 1590B, or just drill the corner pads for using standoffs.
- I mounted the disc cap across the looper chip power supply pins directly to the back of the PCB. One end of a 0.1uF cap goes to pin 12&13, the other end goes to pin 28.
- For the 5 volt voltage regulator, you can use either the 7805 (TO-220 case) or the 78L05 (TO-92 case). The PCB is laid out with the 7805 outline, with the front (the side with the writing) pointing to the right of the PCB. If the 78L05 is used, face the front of it (the side with the writing) to the left of the PCB.

Hope this helps!

[puretube]

soon come: EOL for some of Winbond`s most popular chips...

[The Tone God]

soon come: EOL for some of Winbond`s most popular chips...

Which is one of the reasons I created Payback.

Andrew

[puretube]

soon come: EOL for some of Winbond`s most popular chips...

that`s why I re-bumped this very thread,
so that all subscribed contributers get to read it...

[The Tone God]

that`s why I re-bumped this very thread,
so that all subscribed contributers get to read it...

Link/source ? I don't see anything on their site.

Andrew

[puretube]

large websites are slower than internal emails from large industry-suppliers...
(received today...)

[The Tone God]

large websites are slower than internal emails from large industry-suppliers...
(received today...)

Do you know what lines are going ? (i.e. ISD14xx, ISD25xx, etc.)

Andrew