On & off blinking without micrcontroller

I have a small 5 v DC device I’m trying to power. Because my Elite Notebook is too old to work with Microchip PIC4, I’m trying to use a blinking LED to control the powering of the devise. The idea is for the blinking LED to turn the the device with 1, 5 v DC motor to turn on and off.,
My plan was to have power pass through to On/Off blinking LED. Then tried with and without power a Capacitor to increase the voltage and milliamps to power the activation side of the TLP222AF-ND. It is a SSR Relay.
Then on the load side, I wanted to control powering on and off for a 5v vibrator motor. However, when trying to use it like this I cannot get any blinking on the load end. I only get nothing or constantly on.
I need help to get the device blinking without using a microcontroller due to my limitation on the Elite Notebook


Hi Doug, Welcome back to Digi-Key TechForum. My apologies for this delayed response. We are reviewing your request. Are you able to provide us with a photo of your circuit to help us understand where the LED is located in the circuit and where it is located in reference with the output? What are the specifications of the LED? Thank you Mo

Hello, If you are trying to create a pulse or frequency, you may want to check out 555 timers. Here is a link to the 555 timers we carry:

I will check them out. If they are small, that may work. Here are 3 types of components that may work for my on/off without a microcontroller… I’m not really sure because I don’t design circuits. I have a project coming out that has a budget. I will have a very complexe microcontroller program.
Let me know if you may be interested in helping.

Using a 555 timer will work to control the frequency switching of your SSR. The datasheet of the 555 timer you choose should explain how to use it, and create the frequency you want.

I want to thank you. These look perfect. I think Monday I’ll order a few different ones and do a few experiments.

Let me know if you’re interested in looking at the Microcontroller project I have coking up.


As a side note, self-blinking LEDs voltage will remain constant and not change, therefore it cannot be used to control external circuitry. it is only the current that will fluctuate leading up to the LED. It will usually fluctuate from micro amps (LED off) to milli amps (LED ON).

The flashing LED uses an internal circuit to flash so will not work to turn a circuit on and off. Using a capacitor on the input side will hold the input circuit on until it discharges below the threshold which may not be desirable.

Use a 555 timer and a current limiting resistor to drive the input diode inside the SSR. There are many examples of 555 LED flashers on the net and Digi-Key has all of the components you need. The beauty of the 555 is that it is adjustable so you can tune in your flash rate.

To turn on that solid state relay you would need to supply it current from between 5mA and 25mA with a forward voltage drop of 1.15VDC.

Let’s say you are using Blinking LED PN:

The forward voltage of that led is 3V at lower current like 5mA.
You would subtract your forward voltage of your relay so you would have

( 5V Source Voltage ) - (3V voltage drop of the blinking led ) - ( 1.15V voltage drop of your solid state relay input ) = 0.85V

0.85V left over you need a resistor to draw 5mA of current. 0.85V / 0.005 = 170 Ohm Resistor.

That would maybe work. I’d also look at LED Flasher circuits out there using capacitors and transistors.

thanks, I learned this the hardway