Omnitec FG200 Function Generator

[Deckert]

Hello,

I picked up this old Omnitec function generator for about $50. It was sort-of working, but had lots of noise and some of the rotary switches were almost completely stuck. I little WD40 on the rotary switch pillars and some Servisol contact cleaner inside the switches and the unit was fully working again.

I had to replace one of the knobs (I'll find a more fitting replacement in due course). There is zero information on the 'net about this model, but I suspect it was actually designed and manufactured in South Africa:



Inside, the unit has only three ICs. Two of the chips have their numbers sanded off (why do people do this?!). Looking at the date codes, it seems to have been manufactured in 1981.



It uses an Intersil function gen chip that seems to have been fairly popular at the time:



The ICL8038 data sheet can be found here:
https://www.renesas.com/us/en/search?keywords=ICL8038

The spec sheet says the chip can do 0.001Hz to 300kHz, although the unit I got has a range of 1Hz to about 110kHz. It supports sine, triangle, square and positive/negative pulsing. Looking at the signals it generates on the scope, they're very clean indeed. Not bad for a unit more than 30 years old!

The frequency counter chip seems consistent with the Intersil ICM7216B counter chip.
Edit: a fellow forum user has acquired the same function generator without the numbers scrubbed off. The chip number is actually the ICM7226B (basically the same as the 7216, but with an additional BCD output).



It seems that the ICM7216B was also very popular at the time. The data sheet can be found here:
https://www.renesas.com/us/en/search?keywords=ICM7226

Almost all the functions of the counter chip have been exposed on the unit itself, including period measurement.

Having this unit added to my bench means my XR2206-based project will probably move down the list of projects to be completed. Although it only goes up to 100kHz it serves well to play with analogue signals, RC circuits and investigating their properties on the scope. Measuring frequency output with my trusty RACAL-DANA frequency counter shows that the frequency values displayed on the unit match perfectly. There is a little drift in output frequency as the unit warms up, but after about 10 minutes it stabilizes and there's only a few Hz drift every now and then.

--deckert

Edit: updated with correct chip number and updated the datasheet links.

[Stonent]

I just picked up an XR2206 as well. But I do like that they labeled the pins on most parts, the mosfets and regulators seemed to be marked, good for troubleshooting quickly.