Astable 555 timer - 8-bit computer clock - part 1
Why Electrical Engineering Stack Exchange recommends it
Electronics Stack Exchange users link it as a beginner-friendly walkthrough of the 555 astable circuit, both as a recommended explainer and as the build that askers are following when they run into trouble.
Recommended by 1 people across 1 different months, 2017 to 2023.
What it is
Ben Eater explains how the 555 timer works internally and then builds an astable oscillator on a breadboard, as the first stage of the clock for his 8-bit computer. About the first 15 minutes cover the chip's internal comparators and flip-flop, and the rest covers wiring and tuning it.
What people said
Recommends Arthur · 2017-08 · Electrical Engineering Stack Exchange · on “Why are 555 timers so prevalent?”
A bit off on a tangent, but Ben Eater's 8-bit computer building series has three videos going in-depth about the 555 timer. The first one is here [this video] , and the first 15 minutes of that details the inner workings of the chip, and the rest of the videos tells you how to use it. Without knowing how familiar you are with them, if you want to understand it better, I would say that that's a good place to start.
Cites Robin Theilade · 2017-02 · Electrical Engineering Stack Exchange · on “How to figure out if a 25V capacitor can replace 50V in this circuit”
I'm following this video Astable 555 timer - 8-bit computer clock - part 1 [this video] where he builds this circuit: simulate this circuit [LINK] – Schematic created using CircuitLab [LINK] I just realized that the 1000uF capacitor I have is 25V and not 50V as the one he uses in the video. I suspect that 25V will do but I don't know for sure. I've tested the voltage where the capacitor would have been in the circuit on my multimeter and that reads 55.3mV which is much less that 25V but maybe the 555 timer can change that? Is this a valid way to figure out the maximum voltage the circuit will apply to the capacitor?
Cites Mr Filp · 2019-08 · Electrical Engineering Stack Exchange · on “Astable 555 circuit not oscillating”
@brhans In Ben Eaters video ( [this video] ) you can see at the start that pin 4 is floating. I also tried just now to connect it to Vcc, and it just dimmed the led but the NE555 is still getting extremely hot very quickly and the LED isn't oscillating.
Cites FireGreeks · 2019-09 · Electrical Engineering Stack Exchange · on “Capacitor Discharge Pin 7 555 Timer”
I am very new to electric engineering, so bear with me ;) Before building the circuit IRL, I wanted to try to build a simple 555 timer with a simulator following Ben eater's tutorial on it [this video] . Here are the schematics [LINK] of the circuit... [LINK] If you want to see the tinkercad project [LINK] ... Now, even though I seem to have copied the exact same circuit as shown in the video (or at last so I think) - the first seconds of YT video - the 2uf capacitor doesn't seem to discharge trough Pin 7 when I simulate the circuit. What could be the problem here? I am 100% sure I am missing something very obvious but I have tried, and tried and tried to no avail. So I hope you guys could explai
Cites Dimitris Karagiannis · 2021-03 · Electrical Engineering Stack Exchange · on “Trouble understanding the LM555 schematic for 50% duty cycle oscillator mode”
I am working with a LM555CN [LINK] and I am trying to have it run in astable mode and make a LED blink. In essence I am trying to follow along with this [this video] video. Now, there is a part in the chip instructions where it tells you how to set it up in order to have it run with a 50% duty cycle. [LINK] Here is the part where I am not understanding correctly and I would like someone to explain this to me. [LINK] The way I read this (which is wrong apparently) is that these 2 resistors are connected in series (effectively creating a voltage divider, right? Not right?) where the end of the second resistor goes to pin 7 and the half-way point goes to pin 6 (and 2). In the image attached below, t
Cites zhixin · 2023-04 · Electrical Engineering Stack Exchange · on “Why are the absolute output voltages of the two NOR different in my self-built 555 timer?”
I tried to build a 555 timer using the Multisim live online (free version) [LINK] . I refer to the Ben Eater's video [this video] which I believe referred to the 555 timer datasheet. Here is my circuit and the simulation result. All the settings are default except the output threshold of the amplifier is set as 0-5V. The simulation is as I expected but I don't understand why the absolute output voltage of the two NOR is so much different. Why is the lower output voltage of the NOR gate U3 not 0? The higher output voltage of NOR gate U4 is 1V which is below the high threshold (2V) of the logic gate input. How can that work? You can open my circuit in this link [LINK] . [LINK]