Why the diode in a wall wart hum buster?

Started by Don Kuenz in sci.electronics.design5 years ago 37 replies

Here's what the reverse engineered circuit looks like: X-----> |--------o------------o--------------o Vcc 1N4002 | | ...

Here's what the reverse engineered circuit looks like: X-----> |--------o------------o--------------o Vcc 1N4002 | | | | + | | 470 uF ### 0.1 uF --- 25 V --- --- | | | | X---------------o------------o--------------o Gnd The wall


Low Barrier Height Diodes

Started by Cursitor Doom in sci.electronics.design7 months ago 4 replies

Gentlemen, Can someone suggest a commonly available diode with a very low Vf capable of passing up to 1A continuously and with a reverse...

Gentlemen, Can someone suggest a commonly available diode with a very low Vf capable of passing up to 1A continuously and with a reverse breakdown of at least 24V? A Vf of 0.2V or less would be nice. Thanks.


Reverse polarity, Scotty.

Started by Phil Hobbs in sci.electronics.design8 years ago 57 replies

Hi all, Because of a miscommunication with a client's layout person, I find myself in need of a series-connected dual Schottky diode in SC70...

Hi all, Because of a miscommunication with a client's layout person, I find myself in need of a series-connected dual Schottky diode in SC70 whose pinout is opposite to the BAV54SW, i.e. I need something like this: *------* K ==| | | |== COM A ==| | *------* It'll be used at 20 mA, 12V, no inductive kick. I can use the BAV99RW, but that'll cost m...


varicaps?

Started by John Larkin in sci.electronics.design2 years ago 126 replies

They seem to be getting obsolete. Maybe I can cheat and use a regular pn diode. -- John Larkin Highland Technology,...

They seem to be getting obsolete. Maybe I can cheat and use a regular pn diode. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com


.TEMP in Spice for just one component.

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

how do I specify a different operating temperature for a specific component instead of it applying it to all? .TEMP -32 for example is for...

how do I specify a different operating temperature for a specific component instead of it applying it to all? .TEMP -32 for example is for all the components, but I would like to specify that a DIODE is at like -100 C for example, while every one else is at 38c et.. Jamie


What's the term for this?

Started by Chris in sci.electronics.design6 years ago 41 replies

Say I have a laser diode rated for continuous duty at a Vf=4.5V @ 500mA but I want to push it to a higher power but at a lower duty cycle....

Say I have a laser diode rated for continuous duty at a Vf=4.5V @ 500mA but I want to push it to a higher power but at a lower duty cycle. What's the fancy term for that?


Question about DC- DC boost converter

Started by Daku in sci.electronics.design10 years ago 13 replies

Could some electronics guru please clarify the following ? The following is the basic structure of a boost converter: DC_in -> inductor --> ...

Could some electronics guru please clarify the following ? The following is the basic structure of a boost converter: DC_in -> inductor --> diode --> capacitor --> output | | | | switch | |


Negative logic

Started by George Herold in sci.electronics.design3 years ago 58 replies

I'd like a fast pulse from ground to -5V, is there anything wrong with running logic (74hc10) with Vcc=0 and ground at -5V? I'm not sure how...

I'd like a fast pulse from ground to -5V, is there anything wrong with running logic (74hc10) with Vcc=0 and ground at -5V? I'm not sure how I'll trigger it... maybe on the edge with an RC differential (high pass) and diode.


Weird permeability curve

Started by Piotr Wyderski in sci.electronics.design4 years ago 15 replies

While experimenting with my inductors, the Micrometals design software plotted the following graph (iron...

While experimenting with my inductors, the Micrometals design software plotted the following graph (iron powder): https://s18.postimg.org/gyx3fi989/weird_core.png Why does the inductance rises about 3 times as H increases? This looks very much like a lambda diode, may be useful. Best regards, Piotr


Rectifying RF

Started by Cursitor Doom in sci.electronics.design2 years ago 20 replies

Gentlemen, Say I want to rectify RF of up to 30Mhz so I can read its amplitude with a milivoltmeter, what sort of diode would be suitable?...

Gentlemen, Say I want to rectify RF of up to 30Mhz so I can read its amplitude with a milivoltmeter, what sort of diode would be suitable? I'm guessing I can't use a common 1Nxxxs series jellybean as I would for 50 or 60Hz; I'd need a fast recovery type, yes? And what if the RF in question was only a hundred millivolts or so? That's not enough to overcome the barrier height potential of a ...


Basic Harmonics Question

Started by Klaus Kragelund in sci.electronics.design6 years ago 49 replies

Hi I was just playing with a simulation of a 6 diode rectifier (3 phase input) Mains freqeuency is 50Hz, the harmonics are 250 and 350Hz....

Hi I was just playing with a simulation of a 6 diode rectifier (3 phase input) Mains freqeuency is 50Hz, the harmonics are 250 and 350Hz. The theory is way to long away for me to remember. Why does the 5th and 7th harmonic pop up and no 6th? Thanks Klaus


MOSFET gate protection

Started by circuitmaker in sci.electronics.design5 years ago 4 replies

I have an AC 230V relay built of discrete MOSFETs. Would a 12V 0.3W Zener diode in SOD323 coupled directly to the gates/sources be an...

I have an AC 230V relay built of discrete MOSFETs. Would a 12V 0.3W Zener diode in SOD323 coupled directly to the gates/sources be an appropriate protection against spurious turn-ons/oxide puncture due to high dV/dt on DS or do I need a TVS? c.


Floating above Gnd?

Started by George Herold in sci.electronics.design3 years ago 14 replies

I've got the following two lead circuit measuring the thermal voltage of a diode. (to control temp.) R1 had to be added to keep the circuit...

I've got the following two lead circuit measuring the thermal voltage of a diode. (to control temp.) R1 had to be added to keep the circuit above Gnd, which is a mess at the ~1mV level. Instrment amp. 10uA-> |\ +--OO----+-------|+\ | | | > --- Gnd | +-|-/ | | |/ | | | +--(R1 1


Unconnected part LTSpice seems to need (weird ...)

Started by Joerg in sci.electronics.design10 years ago 81 replies

Folks, This is close to voodoo but repeatable. Unfortunately I can't disclose the schematic since it is for a client. Just wondering , anyone...

Folks, This is close to voodoo but repeatable. Unfortunately I can't disclose the schematic since it is for a client. Just wondering , anyone had this before? At the far end of a TX line I used to have a diode connected across because a previous version of a chip would have such a substrat path. Nice waveforms, fast sims. Everything as expected and peachy. Now the new iteration of the c...


More EDN silliness..

Started by Robert Baer in sci.electronics.design10 years ago 11 replies

Page 66 Dec 15 "..provides more accurate multiplication"?? QSM multipliers have been around for ages; i used to program a Systron Donner...

Page 66 Dec 15 "..provides more accurate multiplication"?? QSM multipliers have been around for ages; i used to program a Systron Donner analog computer that had those. They were "grainy" due to use of diode arrays to create the square law, and results with input(s) near zero had large percent errors. This is a bit better using logs, but... What is all that trash there, wh...


Again with an oops.

Started by George Herold in sci.electronics.design3 years ago 14 replies

I semi-disabled the output of my opa2134 today. Output had right sign at rail, but not enough current. Crappy ascii. |\ ...

I semi-disabled the output of my opa2134 today. Output had right sign at rail, but not enough current. Crappy ascii. |\ v-ref--|-\ don't zener base, diode | > --R_5k--+--| | (pnp 450V) |--gnd Gnd /| | |


Simple pulse stretcher

Started by George Herold in sci.electronics.design9 years ago 94 replies

Hi guys, I need a little digital pulse stretcher. I've got pulses that are 5ns to 25ns in width, and I'd like to bump them all up to all be at...

Hi guys, I need a little digital pulse stretcher. I've got pulses that are 5ns to 25ns in width, and I'd like to bump them all up to all be at least 10ns. I've got a few spare 74HC14 inverters. I was thinking of just feeding one through a diode followed by an R/C to ground. Any other ways? There might be an extra AND gate too. (not my circuit so I'm not quite sure.) Thanks George...


Heat sensing, with IR diode?

Started by Anonymous in sci.electronics.design2 years ago 12 replies

Hi I am way out here on deep water, but here it goes: I need to detect a change in temperature on a black metal surface. Let's say that...

Hi I am way out here on deep water, but here it goes: I need to detect a change in temperature on a black metal surface. Let's say that there is no other option than a contactless method. The sensor is inside a cabinet, so high attenuation to outside light So looking at IR thermal radiation. I do not need an absolute measurement, just a detection if the temperature rises fast An IR...


Negative resistance with BJTs

Started by Anonymous in sci.electronics.design3 years ago 54 replies

a four layer diode, consisting of alternate p, n layers acts as a negative resistance, and can be realized in practice with a pair of NPN and...

a four layer diode, consisting of alternate p, n layers acts as a negative resistance, and can be realized in practice with a pair of NPN and PNP transistors, connected in specific ways. Now, is it possible to achive this a series connection of two discrete diodes ? I was just thinking about it.


OpAmp Voter

Started by SRob...@SpamSucks.net in sci.electronics.design7 years ago 32 replies

I have three DC-5Khz, 0-5 V positive going signals. I'd like to select and = pass the highest of the signals, without diode losses. Using a...

I have three DC-5Khz, 0-5 V positive going signals. I'd like to select and = pass the highest of the signals, without diode losses. Using a microproces= sor is out of the question. Cost is a object and actives should be limited= to devices that can be second sourced.=20 This is for converting a RGB command signal to an intensity signal. Steve=20 =20