# Help starting out

#### lmftit

Joined May 13, 2017
3
Some 35+ years ago I had taken a class in Electronics, so I know some basics, but alas I've probably forgotten most of it. Please excuse the novice level of the questions.

I'd like to try my hand at a small project building a set of flashing LEDs. The general specifications are:

- On-off should be about the same duration
- Frequency will be 10hz to 40hz (not khz!)
- I'm considering using something like
https://www.amazon.com/Chanzon-100pcs-Infrared-Emitter-Emitting/dp/B01BVGIZIU
I want to use a couple of different LEDs ( 1 part red (660nm) to 2 parts (850nm) )

I've looked at

I'm not sure whether I would need a high power project or not or how to identify when it becomes high power.

Also I'm trying to find a quick "kit" on Amazon to get me going. What would be the minimum I would need to get to start out in the way of a kit?

If I don't have an oscilloscope or something like that, any idea how to identify the frequency that is actually being put out?

And if I want to make multiple LEDs flash together, would it be better to put them in parallel or serial?

#### R!f@@

Joined Apr 2, 2009
9,682
Welcome to AAC

Before going into details, your flash rate is quite high to see a visible effect.
10Hz means 10 times per second. That is fast. Above 25 Hz all you see is a tiny flickering.

Can you specify like in how many flashes per second.

#### lmftit

Joined May 13, 2017
3
Welcome to AAC

Before going into details, your flash rate is quite high to see a visible effect.
10Hz means 10 times per second. That is fast. Above 25 Hz all you see is a tiny flickering.

Can you specify like in how many flashes per second.
10hz is an alpha brain wave frequency, 40hz is a gamma brain wave frequency. Think of this as a "Quantlet" type device that aligns with target brainwave frequencies. This isn't a matter of being visible or not. This is to produce light that will be absorbed by mitochondria.

#### R!f@@

Joined Apr 2, 2009
9,682
Oh ! Sorry..My mistake.
So you prefer to buy one as a kit rather than making one.

#### lmftit

Joined May 13, 2017
3
I should probably give a bit more background for folks since I realized that I may be crossing disciplines here

I'm looking to do some experimentation with photobiomodulation and tie that to some neurofeedback concepts. There is no device or kit available for what I'm looking to do. I've only seen a few research papers on things that "might" be similar. I'm looking for a "getting started" kit (like maybe https://www.amazon.com/Elegoo-EL-CK-002-Electronic-Breadboard-Potentiometer/dp/B01ERP6WL4 but I don't know if this would be "enough" to get started).

Basically, I want to bathe the mitochondria in the blood with specific frequencies of light and see how it affects the brain. Some studies doing this have shown different effects depending on the frequency of light application in the range of various brainwave frequencies. I want to build something to reproduce/extend that research.

So I need to create a set of LEDs that flash at various frequencies from 10hz to 40hz with red and NIR LEDs of specific wavelengths of light. Once I accomplish that, I will need to extend the quantity of LEDs until I get the proper amount of light (not lux but I don't remember the metric) of light.

Does this explain it a bit more? (Thanks for the quick responses)

#### #12

Joined Nov 30, 2010
18,159
If I don't have an oscilloscope or something like that, any idea how to identify the frequency that is actually being put out?
Math. We calculate the frequency from the resistor(s) and capacitor(s). The math is never perfect because all parts have tolerances like +/- 5% but math will get you in the ball park and potentiometers will get you some accuracy.
if I want to make multiple LEDs flash together, would it be better to put them in parallel or serial?
Depends on your power supply voltage. If you try to work in old TTL at 5 volts, only the red LEDs will fit 2 in series. If you want to work in 12 volts, you can get 3 or 4 in series, depending on which color they are.

Meanwhile, Wendy has a load of LED flasher circuits worked out in advance. I'll go look for them now.

Here's a list: