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Zener regulator : load and zener current

Started by Anonymous in sci.electronics.design11 years ago 43 replies

In the simple zener regulators like the one below, If the load current is 1= 00ma and zener current is 10ma we calculate the resistor to allow...

In the simple zener regulators like the one below, If the load current is 1= 00ma and zener current is 10ma we calculate the resistor to allow 110ma. If Vin is above Vz and the load draws 50ma, the remaining 60ma flows throug= h zener. What makes it that the remaining current after the load current go= through the zener? Whay can't it be the otherway? i.e after the zener curr= ent the rema...


BJT E-B zener

Started by neo5...@gmail.com in sci.electronics.design1 year ago 48 replies

Where would I go to look for information about using the E-B connection of a 2N3904 as a zener? It has much better leakage than a regular zener...

Where would I go to look for information about using the E-B connection of a 2N3904 as a zener? It has much better leakage than a regular zener but I dont know what kind of power it can handle or how stable it is when used this way.


Zener noise source (freq < 1MHz.)

Started by George Herold in sci.electronics.design12 years ago 12 replies

Zener noise source (freq < 1MHz.) I was revisiting Zener's as noise sources today. I first tried some 12V (1W*) diodes. (I want to bias them...

Zener noise source (freq < 1MHz.) I was revisiting Zener's as noise sources today. I first tried some 12V (1W*) diodes. (I want to bias them from 15V rails.) They worked fine, but I found the noise varied by at least 6dB (a factor of 2 in V peak) for different diodes from the same strip. (After testing 5 I gave up.) So I fell back to an old circuit. +15--+----+ Z | ^


fast, small low-capacitance zener to protect MOSFET gates

Started by Winfield Hill in sci.electronics.design5 years ago 28 replies

I became discouraged of finding a suitable low-capacitance zener to protect the MOSFET gates in my high-voltage amplifier designs. (The...

I became discouraged of finding a suitable low-capacitance zener to protect the MOSFET gates in my high-voltage amplifier designs. (The protection may be optional, but one sleeps better with it in place.) Even the 50uA-rated low-current zener diodes are in fact larger-die types, with high capacitance. For example, the 7.5-volt MMSZ4693 has about 130pF at zero volts. My solution was to us...


Reducing voltage of laptop power supply

Started by Lamont Cranston in sci.electronics.design1 year ago 21 replies

I have a Toshiba 3.4A, 19V laptop power supply that I want to reduce to 12V. Is it as simple as finding a 19V zener and changing it to a 12v...

I have a Toshiba 3.4A, 19V laptop power supply that I want to reduce to 12V. Is it as simple as finding a 19V zener and changing it to a 12v zener? Thanks, Mikek


Dealing with mains power transients

Started by Sylvia Else in sci.electronics.design8 years ago 19 replies

I'm looking at protecting a power sense circuit from mains power transients, using a resistor and a zener diode. Spice says it works well,...

I'm looking at protecting a power sense circuit from mains power transients, using a resistor and a zener diode. Spice says it works well, but when the zener conducts, essentially the entire transient voltage appears across the resistor. A high voltage transient spike is likely to be very narrow, but I can find nothing to say I can put, say, 5000V, across a 1K resistor, even for a micro...


7809 vs 9.1v zener?

Started by Father Haskell in sci.electronics.design12 years ago 7 replies

Low current ( < 100 mA) power supply regulator. Any reason I'd want to use 7809s instead of cheaper 9.1v zeners?

Low current ( < 100 mA) power supply regulator. Any reason I'd want to use 7809s instead of cheaper 9.1v zeners?


Combating Zener Jitter

Started by Chris in sci.electronics.design7 years ago 44 replies

Has anyone got any suggestions as to how to best deal with the phenomenon of jittering zeners? Preferably without adding excessive complexity to...

Has anyone got any suggestions as to how to best deal with the phenomenon of jittering zeners? Preferably without adding excessive complexity to a circuit, I mean.


18v C cell?

Started by Tabby in sci.electronics.design3 years ago 11 replies

Is there an 18v battery about the size of a C cell? A zener tester, probably 1970s, that goes upto 17v max, takes what looks like a single C cell....

Is there an 18v battery about the size of a C cell? A zener tester, probably 1970s, that goes upto 17v max, takes what looks like a single C cell. There is no circuitry that could up the v as far as I can tell.


Zener SOAR

Started by John Larkin in sci.electronics.design7 years ago 21 replies

Well, there don't seem to be SOAR specs on zeners. I suppose I'll have to blow some up. -- John Larkin Highland Technology,...

Well, there don't seem to be SOAR specs on zeners. I suppose I'll have to blow some up. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com


HV indicator

Started by Eddy Lee in sci.electronics.design9 months ago 23 replies

I often have to measure the difference of two 392V sources. Unfortunately, sometimes it become the sum, using a one-time fused muti-meter. I...

I often have to measure the difference of two 392V sources. Unfortunately, sometimes it become the sum, using a one-time fused muti-meter. I am thinking about using a rectifier diode (for direction) , 6V zener (for voltage), 6V 5W light bulb (for current) and 10 ohms resistor. Will it work? Perhaps 22 or 33 ohms resistor?


TVS diode in LT spice

Started by John Larkin in sci.electronics.design2 years ago 4 replies

.model SMCJ33A D(Ron=.4 Roff=8Meg Vfwd=.7 epsilon=100m Vrev=38.65 Vpk=33 revepsilon=4 mfg=Littlefuse type=TVS) That's in the standard library....

.model SMCJ33A D(Ron=.4 Roff=8Meg Vfwd=.7 epsilon=100m Vrev=38.65 Vpk=33 revepsilon=4 mfg=Littlefuse type=TVS) That's in the standard library. It behaves like a symmetric zener. Why? Does "type" do that? There are unipolar TVS diodes, too.


PNPs with high BV_EBO

Started by Phil Hobbs in sci.electronics.design6 years ago 44 replies

I'm doing a Class G driver for a thermoelectric cooler. (I don't want to use Class D because of the switching trash--with Class G it's a lot...

I'm doing a Class G driver for a thermoelectric cooler. (I don't want to use Class D because of the switching trash--with Class G it's a lot easier to get good filtering in a small space.) One issue is that the power supply on the Class G will be only a few volts, and the control electronics is running on +12, so it's easy to zener the BE junctions of various transistors. The 2SD270...


zener!

Started by John Larkin in sci.electronics.design3 years ago 24 replies

https://www.digikey.com/en/products/detail/microchip-technology/JANS1N4102DUR-1-TR/13995295 Somebody must buy them. -- If a man will...

https://www.digikey.com/en/products/detail/microchip-technology/JANS1N4102DUR-1-TR/13995295 Somebody must buy them. -- If a man will begin with certainties, he shall end with doubts, but if he will be content to begin with doubts he shall end in certainties. Francis Bacon


Zenering a big transistor

Started by George Herold in sci.electronics.design7 years ago 57 replies

I'm using a TIP31C (pnp in to-220 pac) as a temp sensor (diode connected) There's a couple of depletion fets in series as current limiters....

I'm using a TIP31C (pnp in to-220 pac) as a temp sensor (diode connected) There's a couple of depletion fets in series as current limiters. (LND150) The b-e junction starts to zener at ~30 V (only two tested so far). So I've got ~1.5 mA flowing at 30 V. Is this going to damage the junction? Will it take time? I'm going to measure forward voltage again after zenering for 15 minutes. Sho...


Simple circuit to flash an LED from RF

Started by amdx in sci.electronics.design2 years ago 27 replies

I'd like to setup a high Q LC to receive a local Radio station probably charging a cap, when the charge is high enough flash an LED. Maybe set...

I'd like to setup a high Q LC to receive a local Radio station probably charging a cap, when the charge is high enough flash an LED. Maybe set the trigger point of an SCR, or could just a zener do it. I don't have LT spice, so please don't post and answer with that.                                 Thanks, Mikek -- This email has been checked for viruses...


Minimilist Level Shifting

Started by Ricky in sci.electronics.design1 year ago 54 replies

I'm tired of digging around looking for an optimal chip to level shift a pair of signals from 5V TTL (an RS-422 transceiver) to 3.3V CMOS. There...

I'm tired of digging around looking for an optimal chip to level shift a pair of signals from 5V TTL (an RS-422 transceiver) to 3.3V CMOS. There are too many devices, and no small number of them are impacted by the semiconductor shortage. But resistors are pretty available, as are Zener diodes. So, I could use a pair of resistors to simply divide the TTL output voltage to somet


Zener noise / oscillations

Started by Robert Baer in sci.electronics.design12 years ago 145 replies

Zeners all seem to behave: quiet, no oscillation IF run at or near the spec current (usually in the tens of mA). But, if one needs to run...

Zeners all seem to behave: quiet, no oscillation IF run at or near the spec current (usually in the tens of mA). But, if one needs to run them at low currents (say 10uA to 500uA) then _watch_out_! Some brands at certain voltages are extremely noisy and subject to oscillation. The waveforms seen at low currents (2-50uA) look like randumb sawtooth generation, and as the curren...


SiC fet gate damage

Started by John Larkin in sci.electronics.design9 months ago 21 replies

Does anyone know anything about the effects of negaive-voltage zenering the gate of a SiC power fet? Specifically, I'm designing a gate driver...

Does anyone know anything about the effects of negaive-voltage zenering the gate of a SiC power fet? Specifically, I'm designing a gate driver for the Cree C2M0280120D and I'm wondering about what might happen in the rare case that I zener the gate by a mA or so. The intent is to drive it -5 to +15, but the -5 could be more in some pathological case. I'll get some from stock later and te...


1N5439: Varactor Diode or Zener

Started by Ed Lee in sci.electronics.design1 year ago 24 replies

I brought and use them as 12V 5W zeners in 32S4P 400V 1A. When balanced, each 1N5439 draws around 400/128 = 3.1W. Occasionally, i got smoke...

I brought and use them as 12V 5W zeners in 32S4P 400V 1A. When balanced, each 1N5439 draws around 400/128 = 3.1W. Occasionally, i got smoke signals with them. No big deal when close to home, but headache trouble shooting on the road. Is there a better part I can use? Some manufacturers list it as "Varactor Diode". https://www.alldatasheet.com/view.jsp?Searchword=1N5439