160 vdc power rabbit hole...

Started by DJ Delorie in sci.electronics.design5 months ago 9 replies

Before I got too far down the rabbit hole... sanity check time :-) tl;dr: I want to run servos off nonisolated 160 vdc background: I'm...

Before I got too far down the rabbit hole... sanity check time :-) tl;dr: I want to run servos off nonisolated 160 vdc background: I'm updating this: http://www.delorie.com/electronics/bldc/ So the old driver used an external motor power supply (I had a 80VDC linear but it's big and used hard to get parts) and a separate external 15V driver supply (closed box switcher). The servos I'...


TPS54302 again

Started by Anonymous in sci.electronics.design6 months ago 3 replies

TPS54302 is a wonderful little synchronous switcher chip. 3 amp switcher in SOT-23, under a dollar. It does radical spread-spectrum pwm but...

TPS54302 is a wonderful little synchronous switcher chip. 3 amp switcher in SOT-23, under a dollar. It does radical spread-spectrum pwm but the dc output is quiet. We're designing a small box that contains about 400 power relays. To reduce coil power, we'll run the relay coils at 12 volts and bump them up to 24 briefly when we change setups. One issue is whether the switcher can switch 2...


Substitute LM2676 simple switcher

Started by g c in sci.electronics.design6 months ago 3 replies

Hi LM2676S-ADJ lead-free are hard to get now. Has anyone tried substituting LM2670 series with success? I am looking at the datasheets trying...

Hi LM2676S-ADJ lead-free are hard to get now. Has anyone tried substituting LM2670 series with success? I am looking at the datasheets trying to find a trap. Not using sync. Need a direct substitute without any changes to surrounding passive parts if possible. Geoff


switcher ringing noise

Started by John Larkin in sci.electronics.design4 months ago 34 replies

I used to love the LTM8078 dual switcher module. But it rings hard at around 400 MHz at every switch transition. This is called a...

I used to love the LTM8078 dual switcher module. But it rings hard at around 400 MHz at every switch transition. This is called a "Silent Switcher!" I breadboarded a 24-to-5 volt switcher with an ancient bipolar LM2576. It switches at 50 KHz. And at every switching edge, it rings at about 40 MHz. We tried all sorts of stuff on both switchers. Nothing so far has any effect on the ringing...


Spice problems

Started by Robert Baer in sci.electronics.design8 years ago 5 replies

Firstly, only the latest LTSpice IV is available,and sources insist only WinXP "or better" will run it. So tried to get old SwitcherCAD...

Firstly, only the latest LTSpice IV is available,and sources insist only WinXP "or better" will run it. So tried to get old SwitcherCAD III; unobtanium. Said, WTF, loaded the LTSpice IV exe, ran it; looks OK - no errors anyway. BUT I have this National Semiconductor Spice file and it barfs on it "Unknown schematic syntax .SUBCKT LM185/27C 99 2" and do not knowhow to fix th...


SF story of unusual electronic device (medical)

Started by C. E. Gee in sci.electronics.design6 years ago 7 replies

Many of my stories offend some group or other while appeasing or pleasing another group opposing the ideals of the first-mentioned group. I...

Many of my stories offend some group or other while appeasing or pleasing another group opposing the ideals of the first-mentioned group. I have managed to construct a story that has the potential of offending two opposing groups. I could not be happier! The April, 2016 Issue of Aphelion Webzine, in their Short Story Department, has published my story "Switcheroo" by C.E. Gee. Be forew...


Maximizing e-cap longevity

Started by Don Y in sci.electronics.design11 years ago 5 replies

Hi, What can I do -- at design time -- to maximize longevity of electrolytics in high frequency switchers? (besides buying good...

Hi, What can I do -- at design time -- to maximize longevity of electrolytics in high frequency switchers? (besides buying good components, derating liberally, etc.) I.e., are efforts at reducing ambient more effective (bang-for-the-buck) than controlling ripple current/internal heating? Any approximate metrics to use in evaluating those efforts (i.e., reducing ambient by 7.2C yiel...


low noise power supply

Started by Jamie M in sci.electronics.design11 years ago 7 replies

Hi, Anyone have a source for a +-12V/200mA+ 5V/2A+ powersupply that has low voltage ripple (ie less than 10mV output ripple)? Most switchers...

Hi, Anyone have a source for a +-12V/200mA+ 5V/2A+ powersupply that has low voltage ripple (ie less than 10mV output ripple)? Most switchers ie: http://search.digikey.com/ca/en/products/PW300MA0012F01/271-2480-ND/1245210 seem to have around 50mV on the 5V rail and 100mV on the 12V rails. cheers, Jamie


Clever ways to get +/- volts from MC34063

Started by Tim Wescott in sci.electronics.design10 years ago 19 replies

I've got a 24V incoming supply, and a need for a number of supplies (+12, +5, -5, and +3.3). The +/- 5V supplies are for a bit of analog...

I've got a 24V incoming supply, and a need for a number of supplies (+12, +5, -5, and +3.3). The +/- 5V supplies are for a bit of analog circuitry on a largely digital board, so they have low current requirements. My plan for the +5V supply is to just hang a 78xx05 off the +12V. +12V and +3.3V are going to come from switchers off of +24V. Anyone have any suggestions for a clever way ...


Dirty switchers ...

Started by Arfa Daily in sci.electronics.design9 years ago 45 replies

> Has anyone seen any good write-ups on, or figured out for themselves, just > how the self-oscillating dirty - i.e. smoothing cap-less -...

> Has anyone seen any good write-ups on, or figured out for themselves, just > how the self-oscillating dirty - i.e. smoothing cap-less - switchers that > you find in use as lamp ballasts (or 'electronic transformers' that they > seem to be sometimes known as) work ? > > I recently acquired a fairly sophisticated disco lighting fixture that has > such a supply to run the 24v 150 watt lamp. I


Synchronous Switchers

Started by John Larkin in sci.electronics.design9 years ago 236 replies

We make a little 4-channel ARB that works fine, but a customer wants to use it in some RF kind of application, and he's seeing...

We make a little 4-channel ARB that works fine, but a customer wants to use it in some RF kind of application, and he's seeing spectral spurs in the -75 dBc sort of range, not too awful for an ARB but terrible by RF generator standards. Turns out there are some mathematical DDS artifacts but the bad boys are switching power supply noise. The main culprits are a couple of LTC3411 synchr...


Resistor TC; was Syncronous Switchers

Started by Anonymous in sci.electronics.design9 years ago 3 replies

From the thread, comment by John Larkin: > > I've mentioned the Susumu thinfilms here more than once. We have a > > huge "tower"...

From the thread, comment by John Larkin: > > I've mentioned the Susumu thinfilms here more than once. We have a > > huge "tower" sample kit that the local Susumu rep dropped off, must be > > a couple thousand resistors. We buy parts down to 0.05% and we are > > measuring TCs in the 5 PPM range. > That's another topic in itself. Take a specified 25ppm TC resistor part, what wo


Flyback vs half-bridge

Started by Phil Hobbs in sci.electronics.design9 years ago 160 replies

So, I'm goofing off playing with small switchers. (Well, not exactly goofing off, but there are somewhat more pressing tasks waiting....) As...

So, I'm goofing off playing with small switchers. (Well, not exactly goofing off, but there are somewhat more pressing tasks waiting....) As I said in George's thread, "Opamp w/ Vsupply > 36V", I built a small half-bridge supply with positive and negative voltage doublers. I'm not that keen on it, because (a) it uses a fair number of parts for what it does, and (b) it has a nasty ins


Synchronous post-rectification

Started by Piotr Wyderski in sci.electronics.design8 years ago 3 replies

Hello, my master power supply provides me with synchronously rectified, but not filtered (!) AC current. For the used 12V toroidal...

Hello, my master power supply provides me with synchronously rectified, but not filtered (!) AC current. For the used 12V toroidal transformer the output waveform is thus 17V*abs(sin(50Hz)), up to 40A. I want to use this supply to power a bank of 10 SEPIC switchers. Issume 20A load in the worst case. It means I must post-rectify the input current in order to feed a big filter capacitor. Th...


some flyback switchers

Started by John Larkin in sci.electronics.design7 years ago 35 replies

I need maybe +750 volts at low current, 15 mA maybe. Here are some attempts to recover some of the leakage inductance energy and keep...

I need maybe +750 volts at low current, 15 mA maybe. Here are some attempts to recover some of the leakage inductance energy and keep the transformer affordable. https://dl.dropboxusercontent.com/u/53724080/Circuits/Power/Flybacks.JPG I got some quotes on PCB mountable HV bricks, and the prices were insane. Maybe I'll make my own, which is more fun anyhow. -- John Larkin ...


Dimmers innards....

Started by David Lesher in sci.electronics.design7 years ago 3 replies

I'm reading a bit on LV lamp dimming. It seems the switchers {"electronic transformers"] that drive 12v Halogens & LED's prefer Reverse-Phase...

I'm reading a bit on LV lamp dimming. It seems the switchers {"electronic transformers"] that drive 12v Halogens & LED's prefer Reverse-Phase dimmers. I'm not seen much of a write up on such but it appears that they turn on at zero crossing, and turn off mid-cycle. The Vizia VPE06-1L is one. I wonder what kind of design they use; power FETs or ???? -- A host is a host from coast to c...


Reflex regenerative receiver again

Started by bitrex in sci.electronics.design6 years ago

So I'm buidling this cool little reflex receiver! It's using a 12EC8 triode/pentode, with the triode performing RF/audio gain duties and the...

So I'm buidling this cool little reflex receiver! It's using a 12EC8 triode/pentode, with the triode performing RF/audio gain duties and the pentode used as the regen amp/oscillator/detector. Power is provided by a 4 "C" cell battery pack and boosted to 12 volts by one of those eBay China special switchers, wrapped up in shielding. The B+ looks pretty clean on my scope so I hope int...


fixed negative LDOs

Started by John Larkin in sci.electronics.design5 years ago 45 replies

There aren't a lot around, and they tend to be expensive. TPS723 looks good, but only comes in -2.5. Microchip has a -3 reg, pin incompatible...

There aren't a lot around, and they tend to be expensive. TPS723 looks good, but only comes in -2.5. Microchip has a -3 reg, pin incompatible of course. Ditto neg-to-neg switchers. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com


EPC2038 GaN fets

Started by John Larkin in sci.electronics.design4 years ago 23 replies

These are really tiny. That's an 0603 resistor on the right https://www.dropbox.com/s/htgdga299yjqvi2/EPC2038.jpg?raw=1 This is the...

These are really tiny. That's an 0603 resistor on the right https://www.dropbox.com/s/htgdga299yjqvi2/EPC2038.jpg?raw=1 This is the smallest of the EPC parts. Most are for power switchers, but this one has low enough capacitances that it might be useful in signal apps. 7 pF Cin is OK, but the 0.02 pF Cdg is something that no mosfet can touch. https://epc-co.com/epc/Products/eGaNFET...


Space race PSUs

Started by Piotr Wyderski in sci.electronics.design3 years ago 13 replies

Hi, what PSUs did they use in the rockets/lunar modules back then in the 60s? Some early switchers or was everything linear? Best...

Hi, what PSUs did they use in the rockets/lunar modules back then in the 60s? Some early switchers or was everything linear? Best regards, Piotr