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Vintage threads from the first ten years

DIY Tremlo

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11/20/1998 2:49 PM

I was looking at Craig Andertons Tremlo schematic and noticed some part numbers that don't cross reference to NTE. One looks like a dual op-amp with the numbers 4739, 5532 and 4558. The other part is an opto-isolator with a part number of CLM6000. Does anyone know what those are and their NTE equivalents?

Or...is there a better (simpler) tremlo circuit I should be looking at?

Thanks!

Bill Harbour

11/20/1998 3:31 PM

Dean Hazelwanter

Actually, I was just discussing some problems that I was having with that circuit with RG. See the thread 'Flying Pan Questions'. The only difference is, I modified the design to have 2 completely separate tremolo circuits driven by the same LFO. If only 1 input is connected, this 1 source continually 'pans' between 2 outputs. We're just in the process of trying to track down a problem where the LFO clock can be heard though the audio.

The 4739 and CLM6000 (as well as the 4136) are not that common. I did a PCB layout for the circuit using the standard (TL072/RC4558 etc) opamp pinout. The CLM6000 (now CLM600) is tougher to find. Mouser can now get them, but you have to buy a minimum of 26, at $7.06 each. I got mine from MCD Electronics about a year ago, minimum order 5 pieces, at $5.25 each. They gave me great service too.

Howard Eckstein
MCD Electronics LTD
(800)949-4623
www.mcdelectronics.com

Hope this helps...

11/20/1998 3:36 PM
Bill Harbour	Speak of the devil....thanks for the reply. I didn't want to put that much money in one. It'd be cheaper for me to locate a used one. Is there another circuit that I could build that would have more up-to-date or easier to find parts? Thanks! Bill Harbour

11/20/1998 4:33 PM
R.G.	I think I detect another question for the FAQ, although this is in the text for the univibe. You can use the Silonex NSL-32, the Vactec VT54C, or make your own with an LED, an LDR, and a chunk of opaque plastic tube cut from a ballpoint pen or other target of opportunity. Newark stocks the Vactec part. Mouser, by the way, is now stocking Clairex photocells, not just the no-name ones.

11/23/1998 7:30 AM
Bill Harbour	R.G. Do you have a drawing somewhere of the LED, LDR and plastic tube optoisolator? Thanks! Bill Harbour

11/23/1998 12:11 PM

I could gen one up, but it's simplicity itself:

Take an opaque plastic tube that is of a size to let you fit the LDR face-first into it. Cut a length of tube that allows the LDR to sit slightly inside the tube and the whole length of the LED to fit in the other end facing the LDR. Place them that way and fill the back end where the leads come out with black, opaque gook, like black RTV or anything else that is non-conductive, sticky, blocks light and sets up hard. Metal tube works as well, just avoid letting any of the leads touch the metal.

All you want to do is face the LED and LDR to one another and block all the ambient light.

11/22/1998 1:56 AM

The choice of op-amp is not that critical. Just use something decent. 8-pin packages like the TL072 and NE5532 are convenient and sound decent, but you can live with a 4558 or a couple of single op amps. The 4739 was good bang for the buck at the time, and more readily available.

In some respects, the optoisolator isn't that critical either since there are many ways in the circuit to compensate for the photocell characteristics (by altering various series and parallel resistance values), and the rise/fall time characteristics are not critical in the circuit.

There are other circuits, but Craig's is generally pretty bulletproof, and amenable to tweaking. The use of an LDR also gets around problems of signal level limits that might occur with, say, FET-based tremoloes.

Incidentally, I've never tried it, but on paper you should be able to turn it into a quasi ring modulator by dropping the values of the cap(s) that set the LFO speed. Bringing the LFO up into the audio range can get some neat rubber band effects.

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