IRF530 is fine: http://seventransistorlabs.com/Images/Discrete_Tube_Supply.png Ignore the filament supply. Isolated windings aren't necessary; you can stack the secondary on the primary, saving that many turns minus Vin. Tim -- Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design Website: http://seventransistorlabs.com "bitrex" <bitrex@de.lete.earthlink.net> wrote in message news:glGuz.3692$Q97.2588@fx06.iad...>I need to throw together a ~150 volt supply at a few 10s of mA to test a >circuit idea, but I don't have much in the way of MOSFETs in my junk box to >build a switcher from. > > The only high-voltage device I have in stock is a couple Fairchild > FQP2N60Cs, rated for 600V and 2 amps. That might be a possibility. > > I also have some lower voltage power devices, and I'm wondering if there > would be a way to cascode two of them for a quick hack to make this work > if I need to. Looks like I have some IRF530s, IRFZ24s, KSC1173 power BJT, > the PNP equivalent KSA473, some MJE350s (high voltage but too low current) > and whatever the NPN equivalent is. > > Anything I can do with this crap?
Junkbox switch for a switcher
Started by ●August 22, 2016
Reply by ●August 23, 20162016-08-23
Reply by ●August 23, 20162016-08-23
On Monday, August 22, 2016 at 1:09:36 PM UTC-4, bitrex wrote:> I need to throw together a ~150 volt supply at a few 10s of mA to test a > circuit idea, but I don't have much in the way of MOSFETs in my junk box > to build a switcher from. > > The only high-voltage device I have in stock is a couple Fairchild > FQP2N60Cs, rated for 600V and 2 amps. That might be a possibility. > > I also have some lower voltage power devices, and I'm wondering if there > would be a way to cascode two of them for a quick hack to make this work > if I need to. Looks like I have some IRF530s, IRFZ24s, KSC1173 power > BJT, the PNP equivalent KSA473, some MJE350s (high voltage but too low > current) and whatever the NPN equivalent is. > > Anything I can do with this crap?I always end up putting a bunch of bench supplies in series. (If it's only for a test.) George H.
Reply by ●August 23, 20162016-08-23
On 08/23/2016 09:01 AM, Tim Williams wrote:> IRF530 is fine: > http://seventransistorlabs.com/Images/Discrete_Tube_Supply.png > Ignore the filament supply. Isolated windings aren't necessary; you can > stack the secondary on the primary, saving that many turns minus Vin. > > Tim >Nice. What's an EA-77-188?
Reply by ●August 23, 20162016-08-23
"bitrex" <bitrex@de.lete.earthlink.net> wrote in message news:4g0vz.5398$e%3.4620@fx07.iad...>> http://seventransistorlabs.com/Images/Discrete_Tube_Supply.png >> > > Nice. What's an EA-77-188?Amidon part number, 0.188" (approx. square) center limb ferrite, #77 mix (so, a Fair-Rite product), E shape. Turns give 0.2-0.3T Bmax, and gap gives the desired inductance (add spacers between core halves, or sand down the middle leg). Most SMPS contain a little transformer that's about the same size, if you don't mind taking one apart and rewinding it. (Hint: superglue is a key disassembly tool...) Tim -- Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design Website: http://seventransistorlabs.com
Reply by ●August 24, 20162016-08-24
bitrex wrote:> I need to throw together a ~150 volt supply at a few 10s of mA to test a > circuit idea, but I don't have much in the way of MOSFETs in my junk box > to build a switcher from. > > The only high-voltage device I have in stock is a couple Fairchild > FQP2N60Cs, rated for 600V and 2 amps. That might be a possibility. > > I also have some lower voltage power devices, and I'm wondering if there > would be a way to cascode two of them for a quick hack to make this work > if I need to. Looks like I have some IRF530s, IRFZ24s, KSC1173 power > BJT, the PNP equivalent KSA473, some MJE350s (high voltage but too low > current) and whatever the NPN equivalent is. > > Anything I can do with this crap?How about a cheap Boost converter module? $12.12 USD DC-DC-12V-24V input to 100V-250V output @ 70W <http://www.ebay.com/itm/131675760033
Reply by ●August 24, 20162016-08-24
Jim Thompson wrote:> On Mon, 22 Aug 2016 16:21:33 -0400, JW <none@dev.null> wrote: > >> On Mon, 22 Aug 2016 15:53:51 -0400 bitrex <bitrex@de.lete.earthlink.net> >> wrote in Message id: <jLIuz.2$j44.0@fx24.iad>: >> >>> They used to make big 45 volt alkaline batteries; they looked like the >>> 9V form factor but about four times longer. I had a couple maybe 15 >>> years ago, I wonder if anyone makes those anymore. >> >> Sure. Google be yer friend, eh? >> >> http://www.batteryjunction.com/exell-415a.html?gclid=CjwKEAjwxeq9BRDDh4_MheOnvAESJABZ4VTqMVOs3gSgtJ4H1T0agjdL8vqD5Y73JmOD6Kqp1PgeShoCOGDw_wcB >> >> http://www.batteryjunction.com/exell-455.html?gclid=CjwKEAjwxeq9BRDDh4_MheOnvAESJABZ4VTqVmk5JkCIFoPPvLaW2kCDma8e-HT2qEvbEV0s74amERoCrtfw_wcB > > There used to be 90V "B" batteries for "portable" radios... I can > still find mention on the web but none of the links seem to work.45 Volt batteries are still available, but they are not cheap. They are still used in Geiger Counters. Do a search for NEDA 202.
Reply by ●August 24, 20162016-08-24
Tim Williams wrote...> >IRF530 is fine: >http://seventransistorlabs.com/Images/Discrete_Tube_Supply.png > > "bitrex" wrote ... >> I need to throw together a ~150 volt supply at a few 10s >> of mA to test a circuit idea, but I don't have much in >> the way of MOSFETs in my junk box to build a switcher from.The IRF530 is an old inferior part. Someone should tell bitrex his FQP2N60C is generally a fine part, suited for a low-current boost supply, using a simple inductor. An IRF530 has too low a voltage rating for a boost converter. bitrex may not have a copy of our new book, but Chapter 9 has 109 pages about power supplies, here's a free sample: http://artofelectronics.net/wp-content/uploads/2016/02/AoE3_chapter9.pdf For 12V to about 150V at say 25mA, the MOSFET, will be on about D = 1-Vin/Vout = 92% of the time (page 647). The 12V input current will be Iout/(1-D) = 300mA. Yes, the FQP2N60C, with 5-ohm ON resistance, will waste 15% of the power, but hey, it's right there in the junk box. A 220uH inductor with 50kHz switching should work fine. -- Thanks, - Win
Reply by ●August 24, 20162016-08-24
Michael A. Terrell <mike.terrell@earthlink.net> wrote:> bitrex wrote: >> I need to throw together a ~150 volt supply at a few 10s of mA to test a >> circuit idea, but I don't have much in the way of MOSFETs in my junk box >> to build a switcher from. >> >> The only high-voltage device I have in stock is a couple Fairchild >> FQP2N60Cs, rated for 600V and 2 amps. That might be a possibility. >> >> I also have some lower voltage power devices, and I'm wondering if there >> would be a way to cascode two of them for a quick hack to make this work >> if I need to. Looks like I have some IRF530s, IRFZ24s, KSC1173 power >> BJT, the PNP equivalent KSA473, some MJE350s (high voltage but too low >> current) and whatever the NPN equivalent is. >> >> Anything I can do with this crap? > > > How about a cheap Boost converter module? $12.12 USD > > DC-DC-12V-24V input to 100V-250V output @ 70W > > <http://www.ebay.com/itm/131675760033I was considering posting "get a CCFL backlight inverter" but it seems they are a bit higer voltage and lower current than what he needs. That converter has more power than he needs, but the price at those outlets is hard to beat. I use those 70cent 3-30V 3A buck converters for everything now, instead of the classic 78xx linear regulator you often had in a small circuit. Have some boost and buck/boost converters in stock as well (e.g. for 12V raw to 12V regulated)
Reply by ●August 24, 20162016-08-24
On 08/24/2016 07:48 AM, Winfield Hill wrote:> Tim Williams wrote... >> >> IRF530 is fine: >> http://seventransistorlabs.com/Images/Discrete_Tube_Supply.png >> >> "bitrex" wrote ... >>> I need to throw together a ~150 volt supply at a few 10s >>> of mA to test a circuit idea, but I don't have much in >>> the way of MOSFETs in my junk box to build a switcher from. > > The IRF530 is an old inferior part. Someone should tell > bitrex his FQP2N60C is generally a fine part, suited for > a low-current boost supply, using a simple inductor. An > IRF530 has too low a voltage rating for a boost converter. > > bitrex may not have a copy of our new book, but Chapter 9 > has 109 pages about power supplies, here's a free sample: > http://artofelectronics.net/wp-content/uploads/2016/02/AoE3_chapter9.pdf > > For 12V to about 150V at say 25mA, the MOSFET, will be > on about D = 1-Vin/Vout = 92% of the time (page 647). > The 12V input current will be Iout/(1-D) = 300mA. Yes, > the FQP2N60C, with 5-ohm ON resistance, will waste 15% > of the power, but hey, it's right there in the junk box. > A 220uH inductor with 50kHz switching should work fine. > >Thanks, that's sort of what I was hoping for. I think I have some suitable inductors too. I'm not big into winding transformers...
Reply by ●August 24, 20162016-08-24
On Wednesday, August 24, 2016 at 9:36:46 AM UTC-4, bitrex wrote:> On 08/24/2016 07:48 AM, Winfield Hill wrote: > > Tim Williams wrote... > >> > >> IRF530 is fine: > >> http://seventransistorlabs.com/Images/Discrete_Tube_Supply.png > >> > >> "bitrex" wrote ... > >>> I need to throw together a ~150 volt supply at a few 10s > >>> of mA to test a circuit idea, but I don't have much in > >>> the way of MOSFETs in my junk box to build a switcher from. > > > > The IRF530 is an old inferior part. Someone should tell > > bitrex his FQP2N60C is generally a fine part, suited for > > a low-current boost supply, using a simple inductor. An > > IRF530 has too low a voltage rating for a boost converter. > > > > bitrex may not have a copy of our new book, but Chapter 9 > > has 109 pages about power supplies, here's a free sample: > > http://artofelectronics.net/wp-content/uploads/2016/02/AoE3_chapter9.pdf > > > > For 12V to about 150V at say 25mA, the MOSFET, will be > > on about D = 1-Vin/Vout = 92% of the time (page 647). > > The 12V input current will be Iout/(1-D) = 300mA. Yes, > > the FQP2N60C, with 5-ohm ON resistance, will waste 15% > > of the power, but hey, it's right there in the junk box. > > A 220uH inductor with 50kHz switching should work fine. > > > > > > Thanks, that's sort of what I was hoping for. I think I have some > suitable inductors too. I'm not big into winding transformers...You could tear up a 12v wallwart smps & run it backwards. That'll get you everything you need, parts-wise. Cheers, James Arthur
