Post by thread:[BUY] PCB Transformer 7VA

Hi, I'm trying to source a small PCB mount transformer for a new project, needs to be cheap and good quality! Primary 240VAC/50Hz and/or 115V/60Hz. Market is two different countries, could be two different transformers with same footprint, or could be dual primary. Secondary 2 x 12VAC or 1 x 24AC CT secondary @ approx 7VA (would consider anything from about 5-10VA). I have found a source for a 240V version here (model 750724)... https://www.soanarplus.com/secure/techfile/7507%20Series1.pdf Price is quite acceptable ~NZ$4.00 (~US$2.50) 100+ qtty, which is great for one target market but they don't seem to do a 115V version. A perfectly good 115/230V dual primary 10VA transformer is found here (model 183G24)... http://www.hammondmfg.com/pdf/5C0010.pdf But price is too high for me, ~NZ$14 (~USD8.50) 100+ qtty. Any suggestions/links to your favourite transformer suppliers would be most welcome! Thanks, Brent. -- Brent Brown, Electronic Design Solutions 16 English Street, Hamilton 2001, New Zealand Ph: +64 7 849 0069 Fax: +64 7 849 0071 Cell/txt: 027 433 4069 eMail: spam_OUTbrent.brownTakeThisOuTclear.net.nz

>Secondary 2 x 12VAC or 1 x 24AC CT secondary @ approx >7VA (would consider anything from about 5-10VA). Could you use a switching supply? I know that ST have some nifty little chips for small VA switchers. I have a copy of their app note AN1484 which describes using their Viper12A chip in a 3.6VA wall wart with 100/230V capability. Not the VA you are after, but they do have bigger chips.

> >Secondary 2 x 12VAC or 1 x 24AC CT secondary @ approx > >7VA (would consider anything from about 5-10VA). > > Could you use a switching supply? I know that ST have some nifty little > chips for small VA switchers. I have a copy of their app note AN1484 which > describes using their Viper12A chip in a 3.6VA wall wart with 100/230V > capability. Not the VA you are after, but they do have bigger chips. Switchers are cool(!) but I think a transformer will be the right choice for this job. I need most of the power at 24VAC to power an actuator, so the two 12V windings will be connected in series. I can then use two diodes and the centre tap to give me full wave rectified 12VDC which will power relay coils and other sub-systems (doesn't need to be regulated). The micro (PIC of course) will just use a +5V linear regulator from the 12V supply as it won't consume much current. Think cheap, bullet proof. Plus the transformer gives me good isolation (definite must have), a built in thermal fuse, and even certification which might mean something. Thanks for the info on the ST chips. I've taken a look now and they are quite interesting. http://www.st.com/stonline/prodpres/discrete/vipower/smps.htm or a ready made power supply (just add diode, fuse and maybe a cap)... http://www.st.com/stonline/products/literature/ds/11101/gs-rxxx12.htm -- Brent Brown, Electronic Design Solutions 16 English Street, Hamilton 2001, New Zealand Ph: +64 7 849 0069 Fax: +64 7 849 0071 Cell/txt: 027 433 4069 eMail: .....brent.brownKILLspam@spam@clear.net.nz

>Plus the transformer gives me good isolation >(definite must have), a built in thermal fuse, >and even certification which might mean something. Yeah, although I don't see anything there that you couldn't get from a switcher. >Thanks for the info on the ST chips. I've taken >a look now and they are quite interesting. They do some real nice devices in the low power off line area. >or a ready made power supply (just add diode, >fuse and maybe a cap)... Pity they do not provide any lab accreditation for it. Would make an interesting device if it did have. Still at that power, I have gone this route http://www.tracopower.com/products/index.htm (third from bottom) which come with UL et al listings.