ICL7660 sub for MAX1044 ?

mat · November 10, 2005, 04:36:36 AM

Hello,

I built the stage center reverb http://www.generalguitargadgets.com/diagrams/stage_center_reverb_lo2.gif on a small hammond box and figured just too late that I cannot feed the circuit with +-9V trough an ordinary 2.1mm DC connector..doh!
Where I live I have not found the MAX1044 chip. Can I sub the MAX with the available ICL7660 chip (same housing) on the chargepumpversion of the SCR http://www.generalguitargadgets.com/diagrams/stage_center_reverb_lo3.gif ,Â is it identical with the MAX chip ? Has anyone used ICL7660 for the charge pump ?

Thanks,
mat

R.G. · November 10, 2005, 05:47:55 AM

It will work in the sense of providing the negative voltage just fine. Just plop in in and go.

Unless you are really, really good at trace and/or wire routing and power supply decoupling, it will also whine at the charge pump frequency of about 6kHz. I've been able to keep power supply noise down to about half a millivolt with these things, but I've been doing this for literally decades. There is no magic key I can tell you to just do it right, either. You have to have everything right, and "right" varies with the physical installation.

Best advice is to put in the 7660, being prepared for whine, then order the MAX1044.

TheBigMan · November 10, 2005, 08:05:35 AM

I've been using the ICL7660S, which has more similar specs to the MAX1044 and also has the boost feature to prevent clock whine like the 1044 has. I started using it because I couldn't find 1044s in the UK.

cd · November 10, 2005, 08:41:47 AM

If you run the 7660 off of an external oscillator, you can pump 50kHz (or more) into it and the whine goes into the inaudible range like a 1044. Do a search in the archive under 7660 with my username, it should bring upa schematic for an oscillator based around a 555 timer.

Paul Perry (Frostwave) · November 10, 2005, 08:55:22 AM

Mat, here's the phone for Maxim in Finland: 0800 114500.
Good luck!!
Alternatively, use a socket, get it running with the 7660, and later get a MAX1044 when you are buying other 'unobtanium' parts from overseas.

mat · November 10, 2005, 12:48:31 PM

Thanks guys for the information, to the each one of You.

I etched the pcb for the chargepump today and will maybe tomorrow populate it with the 7760. The actual part (I got from electronics shop) reads (first logo of a white box with somekind of a 'H' insede it) 7660S IPA H 9307. Will let You know how it turns up.

Paul, I will check the phonenumber tomorrow.

Thanks,
mat

mat · November 11, 2005, 09:37:02 AM

Hi again,

The 7660S IPA H 9307 works just wonderfully, no whine or any kind of disturbing voices.

Paul, I searched info for the phonenumber but no avail. Since the other chip works 100% I will stick to these.

Soundsamples as soon as I get the time to record them..

Thanks,
mat

Paul Marossy · November 11, 2005, 12:43:19 PM

I have some ICL7660s lying about that I was wondering about using. This thread gives me what I nee to know to determine that!

TheBigMan · November 11, 2005, 02:07:01 PM

Quote from: Paul Marossy on November 11, 2005, 12:43:19 PM
I have some ICL7660s lying about that I was wondering about using. This thread gives me what I nee to know to determine that!Â

I've certainly got no complaints Paul. Almost identical to the MAX1044, including pinout. I've got one as a doubler for 18V in an old Ibanez FL-301, works great from a 9V input and is a really nice sounding flanger too.

Paul Marossy · November 11, 2005, 02:20:45 PM

QuoteI've certainly got no complaints Paul. Almost identical to the MAX1044, including pinout. I've got one as a doubler for 18V in an old Ibanez FL-301, works great from a 9V input and is a really nice sounding flanger too.

No high-pitched whining noise?

TheBigMan · November 11, 2005, 02:46:55 PM

Quote from: Paul Marossy on November 11, 2005, 02:20:45 PM
QuoteI've certainly got no complaints Paul.Â Almost identical to the MAX1044, including pinout.Â I've got one as a doubler for 18V in an old Ibanez FL-301, works great from a 9V input and is a really nice sounding flanger too.

No high-pitched whining noise?

None whatsoever. I chose the 7660S over the 7660 because it has the same boost feature as the MAX1044 if you connect pins 1 and 8 directly to +9V. There's a layout in my gallery for a doubler and an invertor.

nelson · November 11, 2005, 05:16:52 PM

Thats strange, The layout for the clone theory I released has been reported to suffer from a high pitched whine.
Maybe If I replaced it with the 7660 in the layout it wouldnt whine.

TheBigMan · November 11, 2005, 08:47:39 PM

Hopefully MartyMart will chime in here. IIRC he's also got a modded FL-301, but I think he used a MAX1044 in his.

Paul Perry (Frostwave) · November 12, 2005, 04:51:08 AM

Quote from: nelson on November 11, 2005, 05:16:52 PM
Thats strange, The layout for the clone theory I released has been reported to suffer from a high pitched whine. Maybe If I replaced it with the 7660 in the layout it wouldnt whine.

Here's a good question: is the whine still there when it is temporarily run on batteries instead? (disconnect the 7660 if you are doinf this test, in case you kill the 7660).
Alternatively, does the whine freq change if you add 20% or so to the oscillator frequency determining cap?

nelson · November 12, 2005, 08:43:28 AM

The noise isnt present with two batteries in series, however currently it is being powered by a MAX1044. I have resigned myself to using two batteries and an 18v PSU. I will probably release a layout that uses the 7660 too.

simon111 · August 16, 2006, 08:25:38 AM

Thought I would bump this up. As if I had read this first I wouldn't have bought a few 7660's.

Just built a clean booster using one, used RG's Charge pump page on Geofex for making a charge pump circuit work. Noticed that he said that 7660's work. So went out and bought a couple.

Tested my boost on the bench and the voltages were fine. Then plugged it in. ARGHHHHHHHHHH

Whining.

Started searching the forum, came across the tying pin 1 and 8 together. Erm, mine has that. Then came across this page.

Read RG's comments. Yep he's right.

Set my signal generator to 6KHz and compared the sound to the whine I am getting from the 7660. Just about perfect pitch match.

So if I replace them with the MAX1044 (EXPENSIVE) then they won't squeal right?

I guess you pay for what you get!

Simon111

Paul Perry (Frostwave) · August 16, 2006, 08:40:34 AM

There is a whole bunch of Linear Technology drop-in equivalents with "improved'(in various ways) specs. It's possible (I can't say for sure) that LT is cheaper or more easily available in some countries than Maxim.

simon111 · August 16, 2006, 09:44:29 AM

Mine were Intersil ICL7660CPAZ to be precise.

petemoore · August 16, 2006, 09:59:48 AM

Is there a schematic Available for the PS board to the left on this page?
http://www.generalguitargadgets.com/diagrams/stage_center_reverb_lo3.gif
I'm working on perfboard, Have some MAX1044's and other Converter chips on the way...and would like to attempt again another effort this year to make my SCR powered without batteries or two WW's.
I was of the understanding that MAX1044's can't supply enough current for the SCR driver...looks like GGG has a diagram ^showing just that tho...
I suppose I can transpose it to a schematic, then populate a perfboard, but if there's a schematic available?
Looking over the wiring and switching, a schematic of only the board to the left would be helpful indeed for sorting what I need only from what is shown. Since I don't have a PCB...

Paul Marossy · August 16, 2006, 10:01:57 AM

Funny, I recently noticed that my Parker Mojo Nitefly piezo pickup system (which has the Fishman "PowerChip" in it) uses an ICL7660 chip and there's no whine. I wonder what they do to avoid that?

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ICL7660 sub for MAX1044 ?