Timeline for What is the Longest Time I Can Set an Astable 555 Timer?
Current License: CC BY-SA 4.0
13 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Sep 26 at 15:22 | vote | accept | Engineer1 | ||
| Sep 25 at 8:02 | answer | added | Whit3rd | timeline score: 2 | |
| Sep 25 at 4:30 | answer | added | Carl Rutschow | timeline score: 2 | |
| Sep 25 at 0:51 | comment | added | Sam | I have been able to reliably get delays on the order of 30s from a 555 (albeit with abysmal accuracy). I needed 10M resistors and a few tens of uF of chip caps. Just FYI, at these timescales CMOS 555s and ceramic/film capacitors are mandatory as the RC charge/discharge currents are minuscule and leakage can be a major headache. If you have to avoid a micro for whatever reason (like I did) but counter ICs are ok, then Carl's solution of a 555 feeding a counter/divider (or several) can get you any delay you like (although a crystal + counter is probably more accurate) | |
| Sep 24 at 18:43 | answer | added | hacktastical | timeline score: 3 | |
| Sep 24 at 17:01 | comment | added | AnalogKid | I love the CD4060, but note that its oscillator frequency is much less stable and predictable than is a 555. This is because the CMOS transition levels are not a tightly controlled parameter, while the 555's famous three resistors ratio-track very well with temperature and aging. | |
| Sep 24 at 16:00 | answer | added | H Price | timeline score: 3 | |
| Sep 23 at 21:39 | history | became hot network question | |||
| Sep 23 at 16:04 | comment | added | vini_i | There are 8 pin micro controllers that can generate such a signal with a minimal amount of programming. They still use RC oscillators internally but they are usually 10% or better. They are also cheaper than the 555. | |
| Sep 23 at 14:14 | comment | added | Andy aka | Reliable timing and 555 don't go hand-in-hand irrespective of the duration. I considered using a 555 just once (around 2012) but didn't bother and, overall, I've been designing electronics for about 50 years. So, that should tell you something. Use a 4060: build-electronic-circuits.com/4000-series-integrated-circuits/… | |
| Sep 23 at 14:09 | answer | added | Spehro 'speff' Pefhany | timeline score: 12 | |
| Sep 23 at 13:57 | comment | added | Carl Rutschow | Yes, long times are problematic with a 555. You could use a 555 along with an IC counter to increase the time. For example set the 555 astable time to 10s (doable) with a counter (e.g. CD4017) set to count 10 pulses, giving a 100s period with a 10s on time. That sound feasible to you? | |
| Sep 23 at 13:36 | history | asked | Engineer1 | CC BY-SA 4.0 |