little HV supply

Started by John Larkin in sci.electronics.design7 years ago 42 replies

Here's a little high-voltage supply. I only need the HV1 (250V) and HV4 (1200V) outputs. It needs tuning, but I need lunch first. Maybe...

Here's a little high-voltage supply. I only need the HV1 (250V) and HV4 (1200V) outputs. It needs tuning, but I need lunch first. Maybe a less fierce mosfet, maybe a bit of snubbing, maybe I'll take the feedback from HV4. I'd prefer less primary inductance in the transformer, but that Coilcraft thing should work. This is to power a pulsed driver into a Pockels-cell-like gadget, for an ...


Adding a ripple to a DC voltage

Started by Anonymous in sci.electronics.design8 years ago 51 replies

Hi all, I have to add a ripple voltage (1Vrms) in serie to a 24V Battery (to build a test bench). The current is about 30A. I was wondering if...

Hi all, I have to add a ripple voltage (1Vrms) in serie to a 24V Battery (to build a test bench). The current is about 30A. I was wondering if a transformer in serie with the battery could do the job. Cheers, H.


LED drivers and itty bitty transformers?

Started by mkr5000 in sci.electronics.design11 years ago 6 replies

Ok, so I buy one of these led driver modules off of ebay, made in china -- they work great and will drive up to FOUR 1W power led's in series at...

Ok, so I buy one of these led driver modules off of ebay, made in china -- they work great and will drive up to FOUR 1W power led's in series at 350ma. The transformer in this thing is really small, maybe a half inch square. It has a 120v input and who knows what out. Something I think I need to bone up on are DC to DC converters because this is where the magic lies, correct? So, if this ...


isolated DC/DC converter

Started by John Larkin in sci.electronics.design11 years ago 189 replies

This http://www.panoramio.com/photo/61564837 might work for powering a thing I'm doing. I can use a standard cheap Coiltronix dual-coil...

This http://www.panoramio.com/photo/61564837 might work for powering a thing I'm doing. I can use a standard cheap Coiltronix dual-coil inductor as the transformer. The complementary emitter followers will have no shoot-through and can have controllably slow switching edges, since they will just follow the base drive. Anybody got ideas for the base driver device? Ideally it would be s...


300V power supply.

Started by George Herold in sci.electronics.design4 years ago 40 replies

Hi all, So I'd like to make a 300 V supply. I don't really want to start from the AC line. So I've been looking for a DC-DC converter...

Hi all, So I'd like to make a 300 V supply. I don't really want to start from the AC line. So I've been looking for a DC-DC converter solution. I started here, (of course) http://www.analog.com/media/en/technical-documentation/application-notes/AN118fb.pdf Figure 13 looked nice. I then priced a pico 32195 transformer. ~$100! Ouch! (maybe I can find a cheaper one.) I then was tr...


PS Filter C in Series, w Parallel R

Started by Warren in sci.electronics.design11 years ago 8 replies

I am planning to build a small power supply, probably (for now) in the range of 18 to 32 VDC after filtering. But I'll be using a transformer...

I am planning to build a small power supply, probably (for now) in the range of 18 to 32 VDC after filtering. But I'll be using a transformer secondary with no center tap and a bridge rectifier. So I was planning to use two filter caps in series, grounding the center point. +)-------+-----+-----> (+) + | | C1 ----- R1 ----- | | | +---


likely donor for 1amp 30v ct transformer?

Started by unk in sci.electronics.design4 years ago 2 replies

This is for a project; need at least an amp at 30v ct. I got one from an junk dotmatrix printer but it's in another project. So I'm looking...

This is for a project; need at least an amp at 30v ct. I got one from an junk dotmatrix printer but it's in another project. So I'm looking for another junk printer, but are there any other likely donors? Old stereo amps?


Bad fuse holders.

Started by Bitrex in sci.electronics.design11 years ago 8 replies

I was finishing up a project earlier today, and on hitting the power switch it's completely dead. It's operated off the line with...

I was finishing up a project earlier today, and on hitting the power switch it's completely dead. It's operated off the line with a transformer, and after a little debugging I realize something is wrong with the fuse, or more specifically, the fuse holder. It's one of the little cup style deals like the one in the bottom right in this image: http://www.hiwtc.com/photo/products/8/02/92/292...


Magnetic field sensitivity of PMT

Started by Joerg in sci.electronics.design7 years ago 72 replies

Folks, Does anyone have experience with operating small switchmode transformers close to a PMT? What I am considering in order to avoid a...

Folks, Does anyone have experience with operating small switchmode transformers close to a PMT? What I am considering in order to avoid a split into multiple boards is to run a Royer with a CCFL transformer on a board that plugs into the PMT. It would also contain the HV ladder, some amps, linear regulators and other stuff. In the trade this whole enchilada referred to as a "socket...


small (3A) AC current measurement

Started by Luis Perez in sci.electronics.design11 years ago 22 replies

Hi guys, I'm trying to measure resistance, current, and voltage of a resistor (heater) connected to a 0-24V @ 3A transformer. The heater's...

Hi guys, I'm trying to measure resistance, current, and voltage of a resistor (heater) connected to a 0-24V @ 3A transformer. The heater's consumption is actually 2A max., and I'd be controlling it with a triac driven with an 8-bit micro, which I'd also use to get the above readings and send them to the host. This is my initial layout: https://docs.google.com/viewer?a=v&pid=explorer...


PSU capacitor choice

Started by Cursitor Doom in sci.electronics.design2 years ago 15 replies

Greetings, gentlemen, I'm attaching a scan of the rectifier board from an HP8547A network analyser. I'm just wondering how the designer(s)...

Greetings, gentlemen, I'm attaching a scan of the rectifier board from an HP8547A network analyser. I'm just wondering how the designer(s) arrived at the choice of value for the caps across the incoming supply from the mains transformer secondary windings (the caps immediately before the bridge rectifiers)? In case you can't make it out, the values are 0.047uF, 0.22uF, 0.47uF and 0.04...


Old power supply issue -- any ideas ?

Started by Anonymous in sci.electronics.design9 years ago 18 replies

Could some electronics guru please help ? I have an old (about 7 - 8 years) +/-15 Volt 2 A power supply that so far has been very reliable....

Could some electronics guru please help ? I have an old (about 7 - 8 years) +/-15 Volt 2 A power supply that so far has been very reliable. It is a standard linear design, with the transformer is rated at +/- 20 Volts 2A max. The output voltage is adjustable via pots at the +/- terminals. Recently, I have been using it to run two CPU style fans that cools a experimental server mach...


Ferrite transformer query.

Started by Clive Arthur in sci.electronics.design5 years ago 32 replies

I use RM8 ferrite cores as signal transformers in the range 10kHz to 100kHz. It's a half duplex system so is switching between transmit and...

I use RM8 ferrite cores as signal transformers in the range 10kHz to 100kHz. It's a half duplex system so is switching between transmit and receive. There's quite a lot of variability in the audible noise from these, some you can barely hear, others there's a pronounced clicking as transmit starts. These have been hand wound by me and others for prototypes. Would a 'proper' trans...


Abusing the LM386

Started by bitrex in sci.electronics.design4 years ago 77 replies

Use two bridged to drive say a little PCB-mount 2k - 8 ohm audio transformer "backwards" to charge a HV capacitor, current feedback from each...

Use two bridged to drive say a little PCB-mount 2k - 8 ohm audio transformer "backwards" to charge a HV capacitor, current feedback from each side of the "primary" inductance keeps the drive current waveform from going all sloppy, cross-coupling the G1 pins boosts each amplifier's "open loop" gain.


Transformer bobbins/coil formers

Started by Clive Arthur in sci.electronics.design3 years ago 14 replies

For an RM ferrite core (RM8 in my case) you can buy two types of bobbin, a single section and two sections, though the latter is less often...

For an RM ferrite core (RM8 in my case) you can buy two types of bobbin, a single section and two sections, though the latter is less often stocked. Assuming there are two windings and that the wire will fit on either type, it seems to me that the two section bobbin would have less inherent inter-winding capacitance and better isolation, though you can't easily wrap a copper tape screen...


strange use of 78** regulators or not ?

Started by M Philbrook in sci.electronics.design4 years ago 9 replies

I do some repair work for my friends now and then and have a Furman Ar- 1220 AC volt line regulator. Original issue was the Triac and...

I do some repair work for my friends now and then and have a Furman Ar- 1220 AC volt line regulator. Original issue was the Triac and opto being shorted for the main primary side so it wouldn't shut the outputs down on extrame voltages. Anyways, while poking around and generating a reversed schematic for it I found it strange that it has a small low current control transformer ...


Power supply connector removal

Started by bitrex in sci.electronics.design6 years ago 9 replies

I'm replacing the old filter electrolytics in this synthesizer power supply; they're starting to get a little crusty. The connectors for the...

I'm replacing the old filter electrolytics in this synthesizer power supply; they're starting to get a little crusty. The connectors for the transformer input and the EL backlight driver output were easy to remove, but I find myself a little stumped on how to remove this one so I can pull it out and get it over to my (small) workbench. Is there any way to easily detach this thing wit...


Eplay

Started by Jan Panteltje in sci.electronics.design10 years ago 24 replies

Sometime ago I tried to make some low voltage oscillators, using JFETs. I have now tried a large quantity of circuits, but this guy break the...

Sometime ago I tried to make some low voltage oscillators, using JFETs. I have now tried a large quantity of circuits, but this guy break the limits: http://www.dicks-website.eu/fetosc/enindex.htm So anyways I copied his last circuit with BF245 JFETs, and with 2 JFETs in parallel connected to a Conrad audio transformer, I get 2 Vpp at the gate with about 40 mV DC supply in, enough to drive...


Guesstimate A Transformer

Started by Anonymous in sci.electronics.design4 years ago 14 replies

One of my useless things I think I'll throw together. An audio amp. I have transformers, audio output transformers from a tube amp that have a...

One of my useless things I think I'll throw together. An audio amp. I have transformers, audio output transformers from a tube amp that have a certain feature I need for this. This is a mobile audio amplifier. The basic configuration is shown at the end of this post in Spice. The coils, L1 and L2 are actually a center tapped winding. What I want to know is how much power dare


DIY CRO Protection HV Probe

Started by Anonymous in sci.electronics.design8 years ago 4 replies

I have been experimenting with HV circuits that generate up to 10KVAC within the audio range. The usual oscillator and step-up...

I have been experimenting with HV circuits that generate up to 10KVAC within the audio range. The usual oscillator and step-up transformer configurations. I would like to check the output waveforms on my digital CRO but don't have a suitable HV probe, and would prefer not to spend $100+ for this one time use. Is there some arrangment of passive components I can wire between the CRO an...