JLCPCB Prototype for $2(Any Color): https://jlcpcb.com
Connecting up a 555 timer as a LED flasher... weirdly.
Connecting up a 555 timer as a LED flasher... weirdly.
By Julian
Youtuber, shed dweller, solar charge controller aficionado
This is just awesome. I hooked up my CMOS 555 with a 10µF cap and a 100k pot in place of the resistor, and there's a really nice range of switching frequencies all at 50% duty cycle. It didn't work until I connected pins 4 and 5, like you said in the video, but it works an absolute charm indeed. Marvellous!
Found this while looking for alternatives to Clive's self-flashing LEDs, could work so there is no need to buy those and it would make the speed customisable. It's kind of swings and roundabouts on the price of 555s vs decent self-flashing LEDs but an A4 board definitely wouldn't be able to have 247 individually controlled LEDs.
I use to operate the astable 555 multivibrator exactly with your resistor capacitor configuration from the output pin, but with a stabilization capacitor at pin 5.
If for 20 blue leds for 9 volts what is the resistor resistance, thank you
Using a 555 and it's discharge pin as a pull down can be part of simple one wire digital interface to so an arduino that read a variable capacitor's value. Just measure the time between pulses.
That said….
There can be strange effects if the capacitor's value is changed quickly/by lots while in circuit. As I discovered experimenting with some anodised titanium and copper tube as a water level sensor… Would get a mild tingle despite running on 5V…. And would then find the 555 had blown… Eventually figured capacitance value was tiny when empty, and more than 100 times larger when full of water. Think there was a voltage step up, when to keep stored energy constant, charged cap had it's capacitance value reduced. Programmable unijunction relaxation oscillator worked better for that application, as trigger when voltage above a set threshold. Not at all difficult to set up to oscillate, if trigger voltage programmed by a constant current through a resistor to ground, and slightly smaller constant current to charge cap, (so PUT can't lock into discharge). Also makes for a linear response/decent ramp waveform.
Hello. I have a simple project idea. I am the would-be novice hobbyist. I need some serious help. How does a person contact you? Would anyone else like to guide me? I'd like to make an American flag with a bunch of LEDs blinking and flashing in an apparent random manner, and also have some constantly on but randomly strobe or flash as though there is a voltage spike or something. I do not wish to employ Arduino (at this point). There are so many component options available and I am confused as to what to choose and why. Please help, folks. Thanks.
sorry silly newbie here but my led does not flash, i have checked the wiring/setup, tried different value resistor and capicitor but guess i've done something wrong somwhere can anyone suggest cap and res values pleaseeee
hi.. new friend here
Are your videos suddenly getting less views? Even though I'm subscribed this didn't show up in my feed.
There are 555 circuits available on the internet where the output pin 3 is feed thu a timing resistor to pin 2 and 6 and then a timing capacitor from pin 2 and 6 to ground.
have a look at the IttyBitty RC Timer/Oscillator MIC1555/57 its a very interesting ic
I've got to go back and update all my old designs. 🙂
Brilliant! This gives an automatic 50% duty cycle.
Tying pin 3 to 5 thru a resistor allows higher R values in the RC timing circuit (or lower C) while maintaining roughly 50% duty cycle.
Might be advantageous in low power applications.
Tying 7 to 5 has an asymmetric duty cycle because the pull down impedance is zero while the pull up is the led/resistor impedance.
What are those white battery connectors?
Nice work Julian. Thanx for all your educational posts. Happy holidays. 🙂
Julian – have you discovered the other way of using it as a monostable?
Especially useful if you need an output (pin 7) to drive a MPU /RESET circuit. Pin 3 can be used as a second/RESET (push/pull) output.
Clever mind bending video Julian. Pushing the limits helps us to grasp of the basic functions of the 555 and to dream up new uses. Good luck outdoing this video, but I would encourage you to continue this series with other components.
"Here, everything's connected up a bit weird."
You and me, both, Julian. 😉
At first glance i thought you got a 555chip with the notch on other side😂