Hi I am on the lookout for a cheap 1:1 pulse transformer. Will be using it to drive a MOSFET based Solid State Switch. I know Larkin has used the DRQ127 https://www.digikey.dk/en/products/detail/eaton-electronics-division/DRQ127-1R5-R/667262 But, I am looking to see if I can find bottom dollar. I probably wont go to LCSC, so would prefer a known brand. Anyone got a recommendation? Cheers Klaus
Cheap pulse 1:1 transformer
Started by ●November 9, 2023
Reply by ●November 9, 20232023-11-09
fredag den 10. november 2023 kl. 00.14.58 UTC+1 skrev Klaus Kragelund:> Hi > > I am on the lookout for a cheap 1:1 pulse transformer. Will be using it to drive a MOSFET based Solid State Switch. >why a transformer instead of an isolated driver?> I know Larkin has used the DRQ127 > > https://www.digikey.dk/en/products/detail/eaton-electronics-division/DRQ127-1R5-R/667262 > > But, I am looking to see if I can find bottom dollar. > > I probably wont go to LCSC, so would prefer a known brand. > > Anyone got a recommendation?seems to me DK has plenty of 1:1 pulse transformers much cheaper than that double inductor https://www.digikey.dk/en/products/filter/pulse-transformers/166
Reply by ●November 9, 20232023-11-09
On Friday, 10 November 2023 at 00:40:13 UTC+1, Lasse Langwadt Christensen wrote:> fredag den 10. november 2023 kl. 00.14.58 UTC+1 skrev Klaus Kragelund: > > Hi > > > > I am on the lookout for a cheap 1:1 pulse transformer. Will be using it to drive a MOSFET based Solid State Switch. > > > why a transformer instead of an isolated driver? > > I know Larkin has used the DRQ127 > > > > https://www.digikey.dk/en/products/detail/eaton-electronics-division/DRQ127-1R5-R/667262 > > > > But, I am looking to see if I can find bottom dollar. > > > > I probably wont go to LCSC, so would prefer a known brand. > > > > Anyone got a recommendation? > seems to me DK has plenty of 1:1 pulse transformers much cheaper than that double inductor > > https://www.digikey.dk/en/products/filter/pulse-transformers/166Yeah, I was looking at those. But except for LAN transformers, they approach 1USD/pcs, which is awful high I was even thinking doing a planar transformer, but production assembly of ferrites are not straight forward
Reply by ●November 9, 20232023-11-09
On Friday, 10 November 2023 at 01:15:37 UTC+1, Klaus Kragelund wrote:> On Friday, 10 November 2023 at 00:40:13 UTC+1, Lasse Langwadt Christensen wrote: > > fredag den 10. november 2023 kl. 00.14.58 UTC+1 skrev Klaus Kragelund: > > > Hi > > > > > > I am on the lookout for a cheap 1:1 pulse transformer. Will be using it to drive a MOSFET based Solid State Switch. > > > > > why a transformer instead of an isolated driver? > > > I know Larkin has used the DRQ127 > > > > > > https://www.digikey.dk/en/products/detail/eaton-electronics-division/DRQ127-1R5-R/667262 > > > > > > But, I am looking to see if I can find bottom dollar. > > > > > > I probably wont go to LCSC, so would prefer a known brand. > > > > > > Anyone got a recommendation? > > seems to me DK has plenty of 1:1 pulse transformers much cheaper than that double inductor > > > > https://www.digikey.dk/en/products/filter/pulse-transformers/166 > Yeah, I was looking at those. But except for LAN transformers, they approach 1USD/pcs, which is awful high > > I was even thinking doing a planar transformer, but production assembly of ferrites are not straight forwardSpeaking of LCSC, it's quite amazing that one can get a transformer like this for less than 10cents: https://www.lcsc.com/product-detail/RJ45-Transformer_CND-tek-TF-1601DG_C408875.html
Reply by ●November 10, 20232023-11-10
On 09/11/2023 23:14, Klaus Kragelund wrote:> Hi > > I am on the lookout for a cheap 1:1 pulse transformer. Will be using it to drive a MOSFET based Solid State Switch. > > I know Larkin has used the DRQ127 > > https://www.digikey.dk/en/products/detail/eaton-electronics-division/DRQ127-1R5-R/667262 > > But, I am looking to see if I can find bottom dollar. > > I probably wont go to LCSC, so would prefer a known brand. > > Anyone got a recommendation? > > Cheers > > KlausDual inductors (like DRQ family) have super coupling but high winding-winding capacitance and insulation is just the minimal enamel so useless for anything HV. I have even used low cost Murata and Panasonic common mode chokes as HV separated gate driver transformers! piglet
Reply by ●November 10, 20232023-11-10
On Friday, November 10, 2023 at 8:34:30 PM UTC+11, piglet wrote:> On 09/11/2023 23:14, Klaus Kragelund wrote:<snip>> Dual inductors (like DRQ family) have super coupling but high winding-winding capacitance and insulation is just the minimal enamel so useless for anything HV.The classic examples are bifilar wound - with twisted pair - and can be 1:1 to one part per billion. They can still have appreciable inductance, but at least it is exactly the same for each side. It takes an effort to get 10:1 ratio transfomers as good as one part in 10 million> I have even used low cost Murata and Panasonic common mode chokes as HV separated gate driver transformers!Sounds credible. -- Bill Sloman, Sydney
Reply by ●November 10, 20232023-11-10
On Thu, 9 Nov 2023 16:30:25 -0800 (PST), Klaus Kragelund <klaus.kragelund@gmail.com> wrote:>On Friday, 10 November 2023 at 01:15:37 UTC+1, Klaus Kragelund wrote: >> On Friday, 10 November 2023 at 00:40:13 UTC+1, Lasse Langwadt Christensen wrote: >> > fredag den 10. november 2023 kl. 00.14.58 UTC+1 skrev Klaus Kragelund: >> > > Hi >> > > >> > > I am on the lookout for a cheap 1:1 pulse transformer. Will be using it to drive a MOSFET based Solid State Switch. >> > > >> > why a transformer instead of an isolated driver? >> > > I know Larkin has used the DRQ127 >> > > >> > > https://www.digikey.dk/en/products/detail/eaton-electronics-division/DRQ127-1R5-R/667262 >> > > >> > > But, I am looking to see if I can find bottom dollar. >> > > >> > > I probably wont go to LCSC, so would prefer a known brand. >> > > >> > > Anyone got a recommendation? >> > seems to me DK has plenty of 1:1 pulse transformers much cheaper than that double inductor >> > >> > https://www.digikey.dk/en/products/filter/pulse-transformers/166 >> Yeah, I was looking at those. But except for LAN transformers, they approach 1USD/pcs, which is awful high >> >> I was even thinking doing a planar transformer, but production assembly of ferrites are not straight forward >Speaking of LCSC, it's quite amazing that one can get a transformer like this for less than 10cents: > >https://www.lcsc.com/product-detail/RJ45-Transformer_CND-tek-TF-1601DG_C408875.htmlIf you stick to core shapes that are used in volume, you can get volume pricing on any drawing and spec from off-shore mfrs. CCFL or LED <8W ballasts, or USB wallwarts are a good place to get an idea of what's used in this market. That's what north american suppliers do, with ~ 500% mark-up. . . . or you can just buy off the shelf from off-shore vendors with one-time-buy volumes. 10K at $0.10 . . . that's a few day's tech labor in NA . . less than you will probably spend to process the paperwork. Sigh. RL
Reply by ●November 10, 20232023-11-10
On Thu, 9 Nov 2023 15:14:53 -0800 (PST), Klaus Kragelund <klaus.kragelund@gmail.com> wrote:>Hi > >I am on the lookout for a cheap 1:1 pulse transformer. Will be using it to drive a MOSFET based Solid State Switch. > >I know Larkin has used the DRQ127 > >https://www.digikey.dk/en/products/detail/eaton-electronics-division/DRQ127-1R5-R/667262 > >But, I am looking to see if I can find bottom dollar. > >I probably wont go to LCSC, so would prefer a known brand. > >Anyone got a recommendation? > >Cheers > >KlausSuggest you nail down your requirements first: Lpmin Vtmin, Rdcmax, Isolation class, prod test level. Many techniques avoid the requirement of high Lp and Vt. Be smart or pay. RL
Reply by ●November 10, 20232023-11-10
On Saturday, November 11, 2023 at 12:28:17 AM UTC+11, legg wrote:> On Thu, 9 Nov 2023 15:14:53 -0800 (PST), Klaus Kragelund > <klaus.k...@gmail.com> wrote: > > >Hi > > > >I am on the lookout for a cheap 1:1 pulse transformer. Will be using it to drive a MOSFET based Solid State Switch. > > > >I know Larkin has used the DRQ127 > > > >https://www.digikey.dk/en/products/detail/eaton-electronics-division/DRQ127-1R5-R/667262 > > > >But, I am looking to see if I can find bottom dollar. > > > >I probably wont go to LCSC, so would prefer a known brand. > > > >Anyone got a recommendation? > > > >Cheers > > > >Klaus > Suggest you nail down your requirements first: > Lpmin > Vtmin, > Rdcmax, > Isolation class, > prod test level. > > Many techniques avoid the requirement of high Lp and Vt. > > Be smart or pay.There's not a lot of smart transformer design discussed here. John Larkin seems to think that you ought to ignore the possibility - anything that you can buy off the shelf trumps anything that you might design, but then again he claims to get away with ignoring the parallel capacitance of transformer windings, which is bizarre, -- Bill Sloman, Sydney
Reply by ●November 10, 20232023-11-10
On Fri, 10 Nov 2023 08:28:15 -0500, legg <legg@nospam.magma.ca> wrote:>On Thu, 9 Nov 2023 15:14:53 -0800 (PST), Klaus Kragelund ><klaus.kragelund@gmail.com> wrote: > >>Hi >> >>I am on the lookout for a cheap 1:1 pulse transformer. Will be using it to drive a MOSFET based Solid State Switch. >> >>I know Larkin has used the DRQ127 >> >>https://www.digikey.dk/en/products/detail/eaton-electronics-division/DRQ127-1R5-R/667262 >> >>But, I am looking to see if I can find bottom dollar. >> >>I probably wont go to LCSC, so would prefer a known brand. >> >>Anyone got a recommendation? >> >>Cheers >> >>Klaus > >Suggest you nail down your requirements first: >Lpmin >Vtmin, >Rdcmax, >Isolation class, >prod test level. > >Many techniques avoid the requirement of high Lp and Vt. > >Be smart or pay. > >RLVolt-second saturation will exclude small parts that othewise look good. Ditto leakage inductance. Winding capacitance, too. There are cases where I would love to drive a fet through a transformer, but nothing reasonable works.
