DDS function generator

This DDS function generator was supplied without a power supply or case. I quickly blew it up!

ICL7660S socketed on DDS fuction generator board
ICL7660S socketed on DDS fuction generator board

This little board only function generator was purchased because it was cheap, quicker and easier then locating a function generator schematic and building one from scratch.

Initially I built a little card board enclosure for it. Without much use it got put away. Then one day I dusted it off and brought it out to play. Then I noticed that the display was working but the selection of frequencies was only showing 10hz steps rather then 1hz increments.

lacking any schematic I set about trying to repair the item and took pictures of various parts of the circuit.

It seems most likely I plugged in a power supply with too much voltage and took out one or more of the integrated circuits.

I noted that one IC7660S-CPAZ was socketed and that integrated circuit was available online and had a data sheet. This showed it as a voltage regulator that can be used to provide duel rails and can also be implemented as a voltage doubler. I ordered a bunch of these and was pleased to see that replacing it resolved the issue.