I was given a bunch of electronics recently and yesterday I was looking through it and found a box labeled 555 and 556s. So I took a 556 out of the box and went back to my office and looked it up on the internet. I then proceeded to build a similiar circuit to yours. I first started with the number 1 side and I got an LED flashing then I added the second side. I used a variable resistor on the 1st side so I can control the speed of the flashing.
Great video Paul, I really enjoy these challenges. I still can’t believe I missed the duel monostable set up. Keep up the very informative and interesting videos.
Great video! There's not too many videos about this IC and I found it very helpful, right now I'm building an oscillating 4-20mA circuit to perform testing and the 556 will do great 👍🏼. Greetings!
One advantage of using 556 instead of an LM555 is that the former do not present the Set/Reset simultaneous issue in the monostable configuration. This problem does not affect the NE555, but the 556 may be an alternative if needed.
Hi, this your video is too much interesting for me. it's a long time i am tryng to realize an circuit with two ne555 in cascade.Example: push start button, IC1 active the first relais for 4 minute, and stop, then pause 3 seconds and start IC2 for X seconds. Then all stop waiting again the button start. do you think it's possible? can you suggest something? Wait an your any answer. Arturo - Italy
I can't the circuit to work as you have. I followed your schematic, but on the board, the leds don't have resistors and 1 leg of the capacitor between pins 5 and 8 is not connected, but there seems to be a direct wire connection ???
Found this video trying to debug a circuit. I tried both sides independently and each ran about 6 seconds. I jumped the output to the second trigger, and get about 12 seconds. They both go to the same relay. I swapped the RC on the jump to 50k and 47uF, but there’s still no delay between. Any ideas?
Ok Paul my bad feel stupid diidnt know of a 556 ic its a another great ic. Is there any more great ics out there that fun and great to build circuits with ? great show and great job you the man
Hi there from soggy Vancouver Island. I was going through the assortment of electronics that I was given and found a 558 quad timer. It has a single VCC and GND and the 4 outputs and each output has a timer and trigger pin. I'd like to do something with 4 LEDs but so far I can't get it to do anything. Could you do a video of this chip?
Wow, I think this is one of the first electronic videos where I could understand what was going on. Could you keep the same size capacitors and control the led on times using a 470k potentiometer in place of the 100k resistors? Or do I need to go to the back of the class and go through the work again? Thank you for taking the time to teach us.
Nice video! I have one question, if you connect pin 5 with 8, when the first timer finished, send LOW to pin 8 and the output 9 keeps high until we click the pushbutton. How dou you do it to stop the second LED after a period of few seconds?
Would ac couple the pin 5 to pin 8 connection via a capacitor. Also use a pull up resistor on pin 8. This would allow only one high to low transistion through the resultant CR coupling when the first half of the timer switches off, unless the first timer is used as a free running astable. This will trigger the second timer through the charge transfer across the coupling capacitor. The pull up resistor prevents unpredictable results from happening. A 10nF to 22nF capacitor is required. I did construct a continuous running circuit by coupling the 2 monostable timer halfs together in this way. However on inspection of the output waveform produced by this circuit on an oscilloscope, found there was brief negative spikes produced. Would be okay in a siren sounder but not when used with flip-flops or counter circuits.
another great video thx. can you maybe show how to make timers that counts time between ttwo input triggers in exsample light diodes as input triggers '
Nice video Paul! and I am getting more interested in the monostable mode. Nice :) Besides that I didn't know this IC existed and I like it :) What I am missing is how this circuit could trigger a bell or a some other more power device. How could the output of 200 mA steering that? I think it must be with a mosfet, relais or transistor or the like, but I have never done that. With an Arduino a simple relais could be attached, but to my understanding a relais draws too much current. Anyway I am interested in a possible next building block for self made creative devices without necessarily using a microcontroller :) Thanks Paul, and have a nice day!
I have connected relays to 555s directly with no issues. Just make sure to use a diode on the coil to protect your chip. Different varieties of these chips exist (probably with different abilities to drive loads) but, I never had a relay damage one.
There are relays with 400 ohms coils. These are marketed as sensitive 12v relays. These could be connected directly. Some datasheets for the 555 family recommend the use of 2 diodes when connecting the relay coil between the 555 output and the 0v rail, one in series with the relay coil going direct to the 555 and the other diode reverse connected across the coil as normal. The dual 556 is about 50mA down in its maximum output current drive ability at 150mA. The maximum output current is about 75mA for the CMOS ICM 7556. There is a marked asymmetry in the drive currents for the CMOS TS555, 100mA when sinking current (output low) but only 10mA when sourcing current (output high).
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