icl8038 , 8038

exar and intersil are BOTH out of production

I cant use the xr2206, I need the 8038.

On page 4 of the datasheet, on the 8038 internal schematic, a few of the transistors have a symbol like a zener bar, why? If I have to build it from surface mount discretes, I will.

Perhaps Schottky clamps? Are they being used as saturated switches?

Cheers,

Phil Hobbs

Doesn't AD have an equivalent?

...Jim Thompson

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Steve, Do you have a link to a schematic?

...Jim Thompson

Probably.

...Jim Thompson

page 4:

-Lasse

You can get them for $20 USD at

Regards, Bob Monsen

Hello Steve,

I agree $51 a pop is outrageous. I have some lying around somewhere. I'd be willing to sell them to you for 10 bucks each. Let me know and I'll look for them. I think they're Harris pieces and I believe they're ceramic DIP's.

Exar Data Sheet:

Intersil:

Steve

if you've got at least 3-4 of them in ceramic I'm game. I use them to repair a early 80s vector graphics generator. It uses the variable symmetry feature to make adjustments in the sweep of the display. .

One local place has them in commercial plastic, but when I went to pick them up the leads were badly corroded to the point of falling off.

Jim, AD has not second sourced the part in a few years.

I'd still temped to reproduce the part myself.

Whats next? the 555? the 741?

Steve

How about $13 bucks for an Exar part, would that be easier to swallow?

Do you need that exact chip and pinout, or just the same functions?

A 2008 way of making those waveforms over a broad frequency range would involve a microcontroller with DAC.

If the frequency range is narrow - especially if the VCO aspects are irrelevant - there are many easy ways to do the job.

Tim.

If I just needed a sine vco, the ad633 data sheet quadrature oscillator works well. What I need is the distortion correction portion of of the 8038, as its used in this application for something other then distortion correction, in this circuit, its tuned from 20hz to 1000 hz, and the waveform shape is changed as part of the function as well. So I'd be looking at programming a micro to do triangle waves and ramps with variable slopes, and the ability to slide from a triangle to ramp in real time.

The fellow who designed the display system was into electronic music, and there are music synthesizer circuits all over the place in this unit. Next up is the CA3280 OTA , both it and the ca3080 are gone. Intersil bought the production line, made as many wafers as possible, and shut down the line. To make most of the former Rca/Harris analog, they have just been dicing wafers as needed. LM13600 is gone too, and LM13700 is on the way out. I can make a adapter board and use a AD633 for the OTA, or just make a simple OTA.

BTW, this is for a laser projection display with vector imaging, these chips do x,y, and z rotations in analog in real time to drive galvanometer scanners.

Thanks, Steve

I was lamenting the CA3046's discontinuation here a few years ago, so I can co-miserate.

I see you already know all about analog multipliers and quadrature oscillators etc. so I don't think I can contribute too much more technically.

But I can ask: what is the "distortion correction potion" of the 8038? Is this the ladder of transistors that makes a nonlinear network converting from triangle to sine waves?

Tim.

see that pot at the top of the demo circuit? By deliberately unbalencing it, things shift in symmetry from reverse ramp to triangle to ramp.

on 2206 they call it distortion correction, on 8038 its symmetry, my bad!

I wish I knew as much about analog as I used to, too many years setting on my posterior supporting the grad students, I've forgotten too much basic EE. Too much time teaching chemists and chemical engineers to measure currents and use a scope, and not enough time with the old pencil and paper. WAY too much time in teh machine shop, and wayyyyyy too much time adapting off the shelf stuff to do the research. I need to get back to the basics and the soldering iron.

I still like the challenge in the idea of designing the drop in replacement in smd, although matching the transistors might be a little hard with just a heathkit curve tracer.

Now to find a chip designer to tell me if all the betas are similar ie standard cells, from transistor to transistor on that design, or if they did a lot of altering things.

Steve