Somebody had an idea for a lossless flyback snubber

Started by Anonymous in sci.electronics.design6 years ago 25 replies

Hey Been trying to find the post with the lossless snubber, with AFAIR a capacitor from the drain node to a regenerative point. I am working...

Hey Been trying to find the post with the lossless snubber, with AFAIR a capacitor from the drain node to a regenerative point. I am working on a 2 switch flyback and some other schemes, but would like to try that novel idea out.... Anyone knows a pointer to the thread? Regards Klaus


Using switched capacitor filter as a variable cut-off anti-aliasing filter

Started by djt294 in sci.electronics.design6 years ago 19 replies

Hi, I have a need to design a 6-pole anti-aliasing filter with a variable frequency cut off range. The highest frequency will most like be a few...

Hi, I have a need to design a 6-pole anti-aliasing filter with a variable frequency cut off range. The highest frequency will most like be a few kilohertz (3K-5K). The first thing that came to mind was a switched capacitor network. It seems to fit the application. My other options seem a bit more complicated (switching in different values of loop components). I have not designed us


Motor capacitor value

Started by Jeff Layman in sci.electronics.design6 years ago 11 replies

Maybe SOT, but I think I've seen discussions here before on motors and capacitors. Basically, how critical is the capacitance to an electric...

Maybe SOT, but I think I've seen discussions here before on motors and capacitors. Basically, how critical is the capacitance to an electric motor (probably start rather than run)? Background... I have a lawnmower with a 1600w motor. A couple of years ago it failed to start, just producing a loud hum and getting very hot. The repair (fortunately still within the guarantee period) state...


SMD -- keeping it simple

Started by mkr5000 in sci.electronics.design6 years ago 22 replies

I don't do elaborate boards with uncommon parts and pitch etc etc. The capacitor and resistor thing is easy enough and I'm going with 0805 for...

I don't do elaborate boards with uncommon parts and pitch etc etc. The capacitor and resistor thing is easy enough and I'm going with 0805 for those (because of small reel sizes for one). For a common 1n series rectifier 4001, 4002 etc I have a choice of melf, mini melf, sod 80,110,123 and 323 in my software. Which is best for something readily available and lowest cost? Also, of the I...


PS12015 power supply, from Velleman and others, LM723 based

Started by Sonnich Jensen in sci.electronics.design6 years ago 2 replies

Hi I have one of these - got it for free: http://www.velleman.eu/products/view/?country=fr&lang=en&id=349761 Mine is from EQ, but it is...

Hi I have one of these - got it for free: http://www.velleman.eu/products/view/?country=fr&lang=en&id=349761 Mine is from EQ, but it is one product with many labels. It works - but... However, there is a burnt diode, V5, which probably was meant for inverse protection - however that diode short circuits the output ???? and the capacitor there is reversed????? I need to either ask f...


Capacitive wireless power transfer question

Started by Anonymous in sci.electronics.design6 years ago 11 replies

Could some electronics guru please shed some light on this ? Consider the following set up. I have an oscillator running at 25 MHz, driving a...

Could some electronics guru please shed some light on this ? Consider the following set up. I have an oscillator running at 25 MHz, driving a 10 pF parallel plate capacitor. The capacitor is made of two single layer copper clad plates of appropriate dimensions, separated by 1.2 mm of FR4. The capacitive reactance at this frequency is about 32 Ohms. What test can I perform to check t...


Phototransistor fed to a transimpedance amplifier

Started by SilverLeo in sci.electronics.design6 years ago 45 replies

Hi all. I'm running through some test of a phototransistor signal conditioner, and I'm facing with wild noise issues. The conditioning is a...

Hi all. I'm running through some test of a phototransistor signal conditioner, and I'm facing with wild noise issues. The conditioning is a basic TIA stage: http://i.imgur.com/PcgglKZ.png Feedback resistor is 5K, feedback capacitor is 470pF, negative bias is -12V, and photocurrent is in the range 8uA-800uA. The bandwidth should be about 50kHz. Opamp is OPA2277UA. Problem is that phototrans...


Film capacitor insulation resistance spec.

Started by Yzordderrex in sci.electronics.design6 years ago 15 replies

Greetings, I am having difficulty interpreting insulation resistance spec. It is on first page. IR C > 400 sec....

Greetings, I am having difficulty interpreting insulation resistance spec. It is on first page. IR C > 400 sec. ..... http://datasheets.avx.com/cb-petht.pdf Can someone interpret? Thanks, Bob N9NEO


Eagle CAD :showing and Pdf printing only capacitor,only diodes...

Started by blisca in sci.electronics.design6 years ago

Hi to all the people here please ,i'm in need to improve my masterhood about Eagle layouts. I was asked to provide a very readable layout...

Hi to all the people here please ,i'm in need to improve my masterhood about Eagle layouts. I was asked to provide a very readable layout paper sheet for mounting by hands smd components,before they go into the soldering oven. When the circuit is populated by many components reading names it is not so easy,large size components names can overlap with each other, small size names are diff...


Get C0G performance up to 0.47uF

Started by Winfield Hill in sci.electronics.design6 years ago 4 replies

C0G and NP0 capacitor dielectrics are popular for their low or zero capacitance change with voltage. However in small SMT packages, 0805,...

C0G and NP0 capacitor dielectrics are popular for their low or zero capacitance change with voltage. However in small SMT packages, 0805, they're only available up to ~ 0.01uF. For higher values we're forced to use X7R, Z5U or other inferior dielectrics. These might change in value by 15% to over 50% at the rated voltage. But, whoa, Kemet has announced a new dielectric, type U2...


Looking for component test clips

Started by Dave M in sci.electronics.design6 years ago 5 replies

I'm looking for a few (about a dozen) of the little connectors like those that are typically found on the small Chinese capacitor checkers. ...

I'm looking for a few (about a dozen) of the little connectors like those that are typically found on the small Chinese capacitor checkers. It's the little slotted connectors into which the capacitor being tested is inserted. It's a metal clip about half an inch wide, and accepts component leads of any size and spacing. I've searched Mouser & Digikey online catalogs, but no luck. You ...


Creating SPICE models

Started by Phil Hobbs in sci.electronics.design6 years ago 19 replies

So I've been designing a Joerg-esque super cheap single diode sampler. With vaguely realistic parasitics, LTspice says it should give a sampling...

So I've been designing a Joerg-esque super cheap single diode sampler. With vaguely realistic parasitics, LTspice says it should give a sampling FWHM of 120 ps or a bit faster, all for well under a buck excluding the timing generation part, but including the pulse speedup part. In the spirit of keeping things cheap and small, I'm using a single JFET switch and a hold capacitor to store the ...


How to make a bipolar electrolytic capacitor from what you have in your junk box.

Started by John Fields in sci.electronics.design6 years ago 15 replies

Let's say you need a > 10 microfarad bipolar cap rated to stand off 10 volts, right away, and and all you have in your junk box is a...

Let's say you need a > 10 microfarad bipolar cap rated to stand off 10 volts, right away, and and all you have in your junk box is a 50 microfarad monopolar aluminum electrolytic rated to stand off 50 volts. If you connect the cap, backwards, to a DC supply and limit the current into the cap to something which won't blow it up, the current into the cap will eventually fall close to zero as


OT: Disconnect capacitor drive before opening

Started by bitrex in sci.electronics.design6 years ago 1 reply

https://www.youtube.com/watch?v=vMaJOjNbnF0 What dt/dq is required to get that baby up to 88 MPH?

https://www.youtube.com/watch?v=vMaJOjNbnF0 What dt/dq is required to get that baby up to 88 MPH?


Harbor Freight battery float charger #42292 circuit?

Started by P E Schoen in sci.electronics.design6 years ago 14 replies

I have one of the cheap ($5) Harbor Freight lead-acid battery float chargers and I found that it was not working (it may have been damaged some...

I have one of the cheap ($5) Harbor Freight lead-acid battery float chargers and I found that it was not working (it may have been damaged some time ago - I had the case open). I traced the circuit and it is basically a FWB and capacitor providing 25 VDC to a 7805 regulator with resistors to set the output to about 13.5 volts. But it also has a TIP41 NPN BJT with a diode and LED to the b...


Schmitt Trigger Jitter

Started by Tim Williams in sci.electronics.design6 years ago 23 replies

Interesting: | Delay (us) | Jitter (ns pk) | 5.7 | 460 | 2.92 | 170 | 1.45 | 26 | 0.72 | <...

Interesting: | Delay (us) | Jitter (ns pk) | 5.7 | 460 | 2.92 | 170 | 1.45 | 26 | 0.72 | < 10 Input is a linear capacitor charging slope. Delay is the time taken from the reset voltage (about 0.5V) until crossing the input threshold. Schmitt trigger is 74HC7014, a very handy little chip. Actually, it's not little, they don't make a TSSOP.


WHOA! Negative Capacitor in LowPass

Started by Jim Thompson in sci.electronics.design6 years ago 16 replies

WHOA! Negative Capacitor in LowPass See... "NegCapacitor_Used_in_LowPass.png" on the S.E.D/Schematics Page of my website. Note the...

WHOA! Negative Capacitor in LowPass See... "NegCapacitor_Used_in_LowPass.png" on the S.E.D/Schematics Page of my website. Note the phase! This was whipped up using idealized components... now to go back and do it with OpAmps and see if it behaves. ...Jim Thompson -- | James E.Thompson | mens | | A...


I need a good text on low noise amplifier design ASAP

Started by Anonymous in sci.electronics.design6 years ago 59 replies

I'm struggling with an amplifier design for a radio front end. Ham 600 meter band (475kHz) The antenna is a ferrite loop (can't change...

I'm struggling with an amplifier design for a radio front end. Ham 600 meter band (475kHz) The antenna is a ferrite loop (can't change that) with a resonating capacitor on the primary, and a few turns on the secondary, so I have a pretty low input impedance. I have several designs in spice, with common emitter and common base configurations, but I am struggling to get the noise below 300...


Capacitor soakage

Started by Prof78 in sci.electronics.design5 years ago 27 replies

Looking for advice/experience on measurement of capacitor soakage. Would like to determine an approximate equivalent circuit for a 1uF...

Looking for advice/experience on measurement of capacitor soakage. Would like to determine an approximate equivalent circuit for a 1uF polypropylene capacitor at very low frequency/time intervals of tens of seconds. Scott Hamilton.


Spice Model Needed...

Started by Jim Thompson in sci.electronics.design6 years ago 8 replies

Spice Model Needed... Does anyone know of a _device-level_ Spice model for a 74HC05 open-drain inverter? I could write one, but there's not...

Spice Model Needed... Does anyone know of a _device-level_ Spice model for a 74HC05 open-drain inverter? I could write one, but there's not a lot of accurate specification information out there. I need a device-level model since my client's application dumps a capacitor. ...Jim Thompson -- | James E.Thompson ...