DIY Optocoupler Transfer Ratio Testing Without Multimeter

If you're interested in testing small components, you might want to check out this article.

Generally, some optocouplers require testing the consistency of the current transfer ratio, which can be done using a multimeter, but it can be a bit messy and temporary. The next time you need to test, you'd have to do it all over again. If you don't want to use a multimeter and prefer a simpler testing method, why not try this DIY solution? This DIY item doesn't require a multimeter, offers relatively easy testing, and provides decent accuracy.

The circuit is quite simple.

For testing, you'll need a U-meter.

For example, when testing this Sharp optocoupler, the process is as follows:

You just need to plug the component into the U-meter.

The display shows 34mA. Since the primary current is 10mA, the secondary current is 24mA, making the transfer ratio 2.4, or 240%.

If you lift the secondary side and only check the primary current, it indeed shows 10mA.

When replacing with another optocoupler, the transfer ratio is 1, or 100%. There is some variation compared to the multimeter's test, as the multimeter shows a range of 80-90%. This difference might be due to varying test currents and voltages.

Removing the optocoupler, there's no current.

Short-circuit the primary with a wire, and the current is still 10mA.

That's it!