Electronics > Beginners
Where to find 230V - 24V transformer
<< < (3/4) > >>
Cliff Matthews:
If OP can find a couple of MOT's, knock out secondary and series-wire primaries for a little extra PSU grunt (cool running too). Just grab some wire and wind-in whatever secondary you need..  :-+
soldar:

--- Quote from: Zero999 on March 26, 2019, 10:00:49 am --- Be careful, some are electronic halogen lamp transformers, work at a much higher frequency, than the mains. They consist of a Royer oscillator driving a small ferrite core transformer and are completely unsuitable for most electronic projects.
--- End quote ---
Be careful? Who? Because I assume someone who is looking for a mains transformer knows what a mains transformer looks like and can tell the difference between a mains transformer and, say, a can of tuna.

But, OK, I will add a disclaimer to my previous post: Do not go looking for mains transformers if you cannot tell the difference between a mains transformer and a can of tuna. ;)
Zero999:

--- Quote from: soldar on March 26, 2019, 11:39:46 am ---
--- Quote from: Zero999 on March 26, 2019, 10:00:49 am --- Be careful, some are electronic halogen lamp transformers, work at a much higher frequency, than the mains. They consist of a Royer oscillator driving a small ferrite core transformer and are completely unsuitable for most electronic projects.
--- End quote ---
Be careful? Who? Because I assume someone who is looking for a mains transformer knows what a mains transformer looks like and can tell the difference between a mains transformer and, say, a can of tuna.

But, OK, I will add a disclaimer to my previous post: Do not go looking for mains transformers if you cannot tell the difference between a mains transformer and a can of tuna. ;)

--- End quote ---
Not you of course, but the original poster. Someone who can't find a 24V transformer, might not know what one looks like. Don't forget this is the beginners section!
mariush:
There's
Farnell : https://uk.farnell.com/c/transformers   - filter further by Isolation Transformers and Toroidal Power Transformers

Note that there's an "official distributor" for Croatia : Altpro D.O.O - see https://export.farnell.com/export-portal  or just try https://export.farnell.com/

RS Components - they have a Croatia sub-site: https://hr.rsdelivers.com/
See  https://uk.rs-online.com/web/c/power-supplies-transformers/transformers/  - filter further by  PCB transformers ,  chassis, toroidal ...

TME.eu - good Polish company, should ship to Croatia : https://www.tme.eu/en/katalog/transformers-and-ferrite-cores_100440/


Also, should be more clear about exactly what you need.

Do you need 24v AC or 24v DC (after rectification using a bridge rectifier, linear regulator etc) ?

Transformers have a VA rating ...

IF you need 24v AC , like for example to light a 75w incandescent lightbulb, then you could go for a 75VA transformer.

if you want to convert output to DC by using a bridge rectifier, then you can approximate the DC voltage and DC current with the formulas:


Vdc peak = sqrt(2) x Vac - 2 x Vdiode  = ~ 1.414 x Vac - 1.5v
Current DC = ~ 0.62 x Current AC

Capacitance required = Current /  2 x AC frequency x [V dc peak - Vdc min]

So for example, if you have a 24v AC transformer with a 100VA rating ( 100VA / 24v = 4.16A) then you'll get a DC voltage with a peak close to 1.414 x 24 - 1.5 = 32v peak and current would be ~ 0.62x4.16 = ~ 2.6A
You'd need C = 2.6 / 2 x 60Hz x (32v - 24v) = 2.6/960 = 0.002708 Farads or ~ 2700uF 50v minimum to keep the DC voltage above 24v at all times.

So if you want a voltage up to 32V DC (depending on how big your smoothing capacitor would be) and up to 3A, you'll need more than 100VA...
exe:
If you go with a transformer, be sure to de-rate it properly (for capacitive load it's about 50% derating is comonly accepted), and take into account mains voltage variation.
Navigation
Message Index
Next page
Previous page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod