Looking for simple circuit ideas to blink/pulse LED strip - Page 1
Forum section: electronics / projects

author: viper
author_rank: Regular Contributor
timestamp: September 05, 2022, 06:52:44 am
content: I have an application where I would like to blink or pulse light from a 12VDC LED light strip. The strip has 3 strips of LEDs, all wired to be separate circuits.I realize simply blinking the lights is simple with a 555 and a pot, but I would like to get a bit more creative and have a few variations of frequency, duty cycle, etc. I would also like to do it differently for 2 of the 3 circuits of LEDs.Basically all I need to do is switch 12VDC to the LEDs and I am not trying to get nuts with frequency, everything well inside of visual spectrum. Maybe 10hz or so. I figure a MOSFET is probably the best for the switching needs.However, in all of this, I am trying to keep this simple without having to bring in a microcontroller. Basically for a mental picture, something like how Christmas lights may have different sequences, but they just repeat. Once I decide on a pattern, I probably won't change it.

author: Ian.M
author_rank: Super Contributor
timestamp: September 05, 2022, 08:29:46 am
content: The problem is the highly complex circuit to do any sequencing without a MCU or other programmable chip. To do anything more complex that variable on and off time flashing, would require a whole mess of counters, gates and other logic and then you have the complexities of how to store and select the sequence.However if you are willing to settle for simple variable on and off time flashing per channel, a CMOS 555 for each channel, with two pots and diode steering so the on and off times can be independently controlled, could be used to drive a MOSFET per channel to switch the LEDs.

author: ebclr
author_rank: Super Contributor
timestamp: September 05, 2022, 11:24:46 am
content: Take a look on CD40106 or any other similar IC , you can play a lot with it

author: tooki
author_rank: Super Contributor
timestamp: September 05, 2022, 03:40:38 pm
content: What’s your goal: a mental exercise on how to do this without a microcontroller, or the simplest circuit possible?For the former, you have many options with varying levels of hardware complexity. For the latter, a microcontroller is undoubtedly the simplest (and the code for blinking isn’t hard, either).

author: capt bullshot
author_rank: Super Contributor
timestamp: September 05, 2022, 03:51:45 pm
content: This should give you some ideas of how to blink LEDs in various ways ...http://wunderkis.de/Blinkenlights/blinkedinger.htmlhttp://wunderkis.de/Blinkenlights/blinkenlights.html(I'm sorry, text is in German, but online translation exists ...)There's no receipes anyway, just stuff for ideas.

author: themadhippy
author_rank: Super Contributor
timestamp: September 05, 2022, 04:28:39 pm
content: Hows about the ole classic 2 transistor astable multivibrator.

author: james_s
author_rank: Super Contributor
timestamp: September 05, 2022, 06:16:26 pm
content: A microcontroller is by far the simplest and most flexible choice if you want more than simple blinking off and on, that's exactly what most holiday lighting that has patterns uses. Another way that was once popular is using an EPROM, drive the address lines with a counter and then program your patterns into it.

author: Zero999
author_rank: Super Contributor
timestamp: September 05, 2022, 09:14:34 pm
content: Quote from: themadhippy on September 05, 2022, 04:28:39 pm

author: TimFox
author_rank: Super Contributor
timestamp: September 05, 2022, 09:22:33 pm
content: I believe that simple battery-operated flickering LEDs (such as to emulate a candle flame) used cheap ICs programmed with simple tunes (e.g., Happy Birthday) designed for use in musical greeting cards.https://www.halloweenforum.com/threads/interesting-fact-about-flickering-led-candles.104046/

author: james_s
author_rank: Super Contributor
timestamp: September 06, 2022, 12:40:11 am
content: Quote from: TimFox on September 05, 2022, 09:22:33 pmSome of them do, others use a LFSR. I don't remember where but somewhere I saw a detailed analysis of several different types of flickering LEDs.

author: viper
author_rank: Regular Contributor
timestamp: September 07, 2022, 10:22:52 pm
content: Thanks for all the thoughts and replies guys! We are moving forward with a microcontroller setup with mosfet switching so we can play around with the tuning a bit easier. Just a one off little project.