555 timer oscilloscope measurements  - Page 1
Forum section: electronics / beginners

author: Gazmon
author_rank: Regular Contributor
timestamp: March 09, 2019, 09:02:11 pm
content: Hi all,I built a 555 timer flashing Led circuit in a breadboard , yes pretty basic but would really like to use my new oscilloscope to take some readings and get experience using itIt’s running at 5v , looking for tips on what and how I can use the oscilloscope to take measurements and waveforms etcRunning it from my power supplyAny help appreciatedGazmon

author: GeoffreyF
author_rank: Regular Contributor
timestamp: March 09, 2019, 10:45:17 pm
content: assuming everything is normal - just do it. The best way to learn electronics is to try things and take chances.The worst you can do is ruin an oscilloscope probe and therefore:Oscilloscope set for 5v?Probe 1:1Assume the power supply ground and the oscilloscope ground are similar? Check with a DVM to be really sure.

author: Gazmon
author_rank: Regular Contributor
timestamp: March 09, 2019, 10:52:10 pm
content: So I can connect my ground probe to the 0vAnd my probe to 5v Vcc in etcAs long as my 0v is connected to my ground probe am I ok to hook on the pulse etc that flash’s etc

author: IanMacdonald
author_rank: Frequent Contributor
timestamp: March 09, 2019, 10:57:37 pm
content: As a general principle I always use a x10 probe unless measuring millivolt levels. That way, if it accidentally gets put onto high voltage it's far less likely the scope will be damaged.A habit from CRT TV maintenance days. It also means less circuit loading. When on x10 you need to compensate the probe for this particular scope otherwise your readings will be way out. The manual should tell you how.To find the right vertical range just start at a low setting and increase until waveform is large enough to read comfortably. The scale is in volts/division so 1v/division would be suitable here. 5v/div will only give a one-division high trace.As for grounding, depends if the PSU output is grounded or not. Generally it will not be. However, if the PSU negative is grounded then that is the only place you can attach the probe ground clip.

author: TK
author_rank: Super Contributor
timestamp: March 09, 2019, 11:01:03 pm
content: Quote from: Gazmon on March 09, 2019, 10:52:10 pmYes, that is what oscilloscopes are used for. Just keep out of mains, it is dangerous. And connect the probe to something more interesting than 5V... like pin 3 on the 555 (output), etc. to see some moving trace

author: Gazmon
author_rank: Regular Contributor
timestamp: March 09, 2019, 11:15:53 pm
content: I’m using a Tenma 30v /3A bench power supplyJust connected to live and neutral outputs at 5v settingGuessing that hooking onto 0v on my breadboard gives me my reference base

author: Brumby
author_rank: Unknown
timestamp: March 10, 2019, 12:14:30 am
content: Quote from: Gazmon on March 09, 2019, 11:15:53 pmA suggestion: Do not use "live" and "neutral" for theoutputsof a power supply. Those terms are pretty much exclusively used for mains power.If you use them for power supply outputs, many people are going to think "mains" and go into "protect the newbie" mode, giving you all sorts of warnings that aren't going to make sense.

author: Brumby
author_rank: Unknown
timestamp: March 10, 2019, 12:15:40 am
content: If you are new to scopes, then this is worth watching (pretty much a standard recommendation, in fact)...

author: Gazmon
author_rank: Regular Contributor
timestamp: March 10, 2019, 01:00:32 am
content: Quote from: Brumby on March 10, 2019, 12:14:30 amyep ok I mean 0v and 5v low voltage supply

author: Brumby
author_rank: Unknown
timestamp: March 10, 2019, 01:22:31 am
content: That's much better. Everyone will understand that immediately.