DIY step down transformer

rhapsodee · 23rd May 2009, 04:21 PM

Hi Guys,

I'm trying to diy a step down transformer to operate a 110V brad nailer from my 230V wall source.

Is it just a matter of getting a toroidal core, and winding a 2:1 primary to secondary coil ratio?

I did that, and when i tried plugging it into the wall socket, well the fuse tripped. This was with the secondary winding open circuit - i was planning to measure it using a multimeter to make sure i got the number of coils and hence voltage ratio correct.

This got me thinking, with no load on the secondary winding, how is the current in the primary winding controlled? I'm thinking it has to do with the inductance, or complex resistance, which prevents the primary winding from drawing too much current? How does a load on the secondary winding affect this? By reducing the inductance, and hence increasing the current in the primary winding?

This would be the load on the brad nailer, which only draws current when fired. Otherwise it would be open circuit...

Does that mean i have too low an inductance on my primary winding, hence it is drawing too much current and tripping the fuse?

Sorry if i am going in circles. I think i need some help here. The stuff i found online about transformers seem rather generic, nobody mentioned anything about fuses tripping when you connect the primary winding to the mains source...

Thanks a lo!!!

AndrewT · 23rd May 2009, 04:29 PM

it's a case of buying a 220/240Vac:55+55Vac transformer.
Wire the two secondaries in series for your 110Vac feed to the nailer.

rhapsodee · 23rd May 2009, 04:49 PM

Andrew,

Thanks for your reply. I already have a toroid core, and some wires lying around, so i was trying to make it work. Does the absolute number of coils matter?

Thanks!

SY · 23rd May 2009, 05:02 PM

May I be perfectly honest with you? These are all excellent questions you're asking and I'm glad to see you asking them. Primary inductance for the frequency and load is a vital consideration.

But the fact that you're asking these excellent questions would make me STRONGLY advise you not to try winding your own mains-based high power transformer from scratch until you get more experience. This is a serious safety issue. Buy a stepdown transformer or do as Andrew suggests.

rhapsodee · 24th May 2009, 03:16 AM

Thanks for the advice and clarifications.

23rd May 2009, 04:21 PM	#1
rhapsodee diyAudio Member Join Date: Jun 2005 Location: Singapore	DIY step down transformer Hi Guys, I'm trying to diy a step down transformer to operate a 110V brad nailer from my 230V wall source. Is it just a matter of getting a toroidal core, and winding a 2:1 primary to secondary coil ratio? I did that, and when i tried plugging it into the wall socket, well the fuse tripped. This was with the secondary winding open circuit - i was planning to measure it using a multimeter to make sure i got the number of coils and hence voltage ratio correct. This got me thinking, with no load on the secondary winding, how is the current in the primary winding controlled? I'm thinking it has to do with the inductance, or complex resistance, which prevents the primary winding from drawing too much current? How does a load on the secondary winding affect this? By reducing the inductance, and hence increasing the current in the primary winding? This would be the load on the brad nailer, which only draws current when fired. Otherwise it would be open circuit... Does that mean i have too low an inductance on my primary winding, hence it is drawing too much current and tripping the fuse? Sorry if i am going in circles. I think i need some help here. The stuff i found online about transformers seem rather generic, nobody mentioned anything about fuses tripping when you connect the primary winding to the mains source... Thanks a lo!!!

23rd May 2009, 04:29 PM	#2
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	it's a case of buying a 220/240Vac:55+55Vac transformer. Wire the two secondaries in series for your 110Vac feed to the nailer. __________________ regards Andrew T.

23rd May 2009, 05:02 PM	#4
SY diyAudio Moderator Join Date: Oct 2002 Location: Austin, TX Blog Entries: 1	May I be perfectly honest with you? These are all excellent questions you're asking and I'm glad to see you asking them. Primary inductance for the frequency and load is a vital consideration. But the fact that you're asking these excellent questions would make me STRONGLY advise you not to try winding your own mains-based high power transformer from scratch until you get more experience. This is a serious safety issue. Buy a stepdown transformer or do as Andrew suggests. __________________ “Listening to records is like ****ing a picture of Brigitte Bardot.” - Sergiu Celibidache

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23rd May 2009, 04:49 PM	#3
rhapsodee diyAudio Member Join Date: Jun 2005 Location: Singapore	Andrew, Thanks for your reply. I already have a toroid core, and some wires lying around, so i was trying to make it work. Does the absolute number of coils matter? Thanks!

24th May 2009, 03:16 AM	#5
rhapsodee diyAudio Member Join Date: Jun 2005 Location: Singapore	Thanks for the advice and clarifications.

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