220 and 110 V  - Page 1
Forum section: electronics / beginners

author: darinsquared
author_rank: Contributor
timestamp: November 09, 2019, 02:55:43 pm
content: Newbie question.When making an electronics circuit from examples found on the internet most are written using 220v European standard. If I want to make the circuit using 110v N American standard what do I need to adjust? I have seen where you reduce the resistor to half. But does this apply to every resistor and what other changes are required?

author: rstofer
author_rank: Super Contributor
timestamp: November 09, 2019, 03:33:02 pm
content: I think your question is circuit dependent. You can post individual circuits and learn from any explanations you get. Of course, it matters where you are getting the explanations and who is giving them. Threads are pretty good because there will always be a consensus. Reading a one-off post somewhere on the Interweb is probably not a good explanation.Many circuits use a transformer. The only change in this case might be the transformer primary voltage. If it doesn't use a transformer, don't even think about building the circuit. Having mains voltages running all over the place is risky.And, no, dividing by two won't be the case for EVERY resistor. Without a schematic, we can't even determine if it applies to ANY resistor.

author: tooki
author_rank: Super Contributor
timestamp: November 09, 2019, 06:10:27 pm
content: FYI, remember that North America has actually been 120V, not 110V, for nearly 100 years. Doesn’t matter in most circuits, but better to design around the actual voltage.

author: IanB
author_rank: Super Contributor
timestamp: November 09, 2019, 06:29:13 pm
content: Quote from: darinsquared on November 09, 2019, 02:55:43 pmYou won't like this answer, but if you are a newbie you should not be looking at circuits that use mains voltage. Lack of knowledge is dangerous around the mains.Nearly all circuits using transistors, ICs and micros will be powered from a low voltage supply, e.g. 5 V or 12 V. These are easily powered by a mains adapter or USB charger suitable for the country you live in. These are the circuits you should be considering to build and there is no danger from mains voltage.(I am not a newbie and I still get really nervous if I have live mains anywhere on my workbench. Far better to use a standard low voltage power supply.)

author: darinsquared
author_rank: Contributor
timestamp: November 10, 2019, 01:57:30 pm
content: I understand the risks. I work a bit around electricity just not circuitry. I am also looking at the options you mentioned but I want to understand how these circuits works. I want to try something basic like led light array and a simple PIR activated relay switch. I was looking at circuit to install a LED light into a 110V extension cord similar to the cords you can buy. (mine for some reason melted inside) I was just wondering if I Could replicate it on my own.

author: soldar
author_rank: Super Contributor
timestamp: November 10, 2019, 03:41:40 pm
content: Quote from: darinsquared on November 10, 2019, 01:57:30 pmThe melting extension cord is very easy to replicate. I do not think you would have any problem doing it.

author: andy3055
author_rank: Super Contributor
timestamp: November 10, 2019, 04:33:55 pm
content: IanB hit the nail on the head so to speak. After 50+ years of experience, I still take extra precautions when I have to deal with anything that has exposed mains voltages.

author: SiliconWizard
author_rank: Super Contributor
timestamp: November 10, 2019, 04:40:01 pm
content: Quote from: tooki on November 09, 2019, 06:10:27 pmLikewise, in other countries it's now often 230V or even 240V. The EU mains standard is typically 220V-240V range. A circuit that would work at 220V and not at 240V would be poorly designed, and could even be a hazard.https://en.wikipedia.org/wiki/Mains_electricity_by_country

author: Gregg
author_rank: Super Contributor
timestamp: November 10, 2019, 06:24:53 pm
content: To get back to the OP's question (but I did laugh at soldar's comment on melting extension cords):Why not use a neon lamp and a resistor for the simple, cheap and reliable indicator. Sometimes old school solutions are still viable.The female molded extension cord receptacles are sometimes garbage as the plastic gets into the space for the prongs of the plug and causes a bad connection.

author: tooki
author_rank: Super Contributor
timestamp: November 11, 2019, 02:07:01 am
content: Quote from: SiliconWizard on November 10, 2019, 04:40:01 pmYep. It can even exceed 240V in the “former” 240V countries. (When the 220 and 240V countries harmonized to 230V, it was specced as 230V, -6% to +10%, which works out to 216-253V, covering the combined tolerance ranges of the old 220 and 240V standards.)

author: darinsquared
author_rank: Contributor
timestamp: November 11, 2019, 02:07:15 pm
content: I have replaced the melted end with just a regular end. I have done that several times with other cords. I would like to have the light to verify current, I do no think you can buy replacement lighted ends.

author: Nusa
author_rank: Super Contributor
timestamp: November 11, 2019, 02:33:05 pm
content: Quote from: darinsquared on November 11, 2019, 02:07:15 pmSure you can, just google "lighted extension cord ends". But the light only indicates voltage, not current. Current happens when you start using it.There's also stuff like this (https://www.truevalue.com/clear-lighted-end-grounding-adapterorhttps://www.amazon.com/MaxWorks-80696-Outdoor-Extension-Lighted/dp/B071ZR3SZJ/) to add to your non-lighted cords.

author: langwadt
author_rank: Super Contributor
timestamp: November 11, 2019, 02:56:59 pm
content: Quote from: tooki on November 11, 2019, 02:07:01 amI believe the spec is now the same everywhere, 230V +/-10%

author: tooki
author_rank: Super Contributor
timestamp: November 11, 2019, 06:04:46 pm
content: Sorry, yes, you're absolutely right, I forgot to say "during the transition period", when various weird tolerances were implemented. (Googling in English, when I first wrote, didn't lead to as clear an explanation as I found just now by searching in German.)

author: m3vuv
author_rank: Super Contributor
timestamp: November 11, 2019, 08:46:49 pm
content: this guys lack of knowlege sounds like an accident looking for a place to happen!!

author: forrestc
author_rank: Unknown
timestamp: November 12, 2019, 03:16:38 pm
content: Quote from: andy3055 on November 10, 2019, 04:33:55 pmI don't know if it is necause of experience, knowledge, wisdom, or just becoming a bit more risk adverse as I get older, but I find that as I've gotten older, my desire to bring mains voltage anywhere near my circuits has decreased drastically.Some of my early experiments were computer controlled lighting controls, assembled with great ignorance. I'm surprised I didn't burn anything down. I still have one assembled carefully in a wooden box with inadequate standoffs. And no I don't use it anymore. It's simultaneously frightening and also amazing that I succeeded in making this work.For the OP: there are lots of interesting projects out there which don't directly connect to the mains, and instead connect using a certified power adapter, such as a USB charger. In fact a couple of the projects you described would work this way.For instance one can buy pir sensors which would run off 5V which is USB voltage. You can also buy safe relays to control with them or with other circuits (look up DLI IoT relay).The LED light array also wouldn't need direct AC connection.I'd just skip anything which connects directly to the AC line.

author: soldar
author_rank: Super Contributor
timestamp: November 13, 2019, 08:16:41 pm
content: Quote from: forrestc on November 12, 2019, 03:16:38 pmSame here. I was disassembling something I built decades ago and I was shocked to see 220 Vac everywhere and very close to the metal case. I would never build something like that today.

author: ender4171
author_rank: Contributor
timestamp: November 15, 2019, 07:52:33 pm
content: It depends on the circuit. Most switching supplies don't care if you feed them 110 or 220. If you have a circuit that uses a transformer or a linear supply you might need to change out some components. Pretty much anything with an IC is going to actually run at low DC voltage. In the case where you can't run a circuit off either AC voltage, you just need to look at the schematic/block diagram, determine what parts are the power supply, and modify the components/values to suit your voltage. For instance, say you had a simple 555 timer circuit that was driven by a 220v to 12v transformer, rectifier, and filtering circuit. You would change out the transformer and anything before it with equivalent 110v versions. Once you get to the LV DC part of the circuit, it shouldn't need any modification.