Zener regulator : load and zener current

Started by Anonymous in sci.electronics.design9 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...


Zener noise source (freq < 1MHz.)

Started by George Herold in sci.electronics.design11 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.design4 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...


LTspice Zener Models

Started by Rick C in sci.electronics.design3 years ago

I'm looking to model a circuit with a zener diode in it and the exact part doesn't seem to have a simulation model. Looking at the 11 choices in...

I'm looking to model a circuit with a zener diode in it and the exact part doesn't seem to have a simulation model. Looking at the 11 choices in LTspice I see a variety of parameters. The one that I'd probably want to match the most closely is the source resistance, Rs. This seems to be a very difficult number to pin down. The part in question is CZRU52C6V2 by Comchip. They l


Zeners in Series

Started by Cursitor Doom in sci.electronics.design3 years ago 80 replies

Whilst mere hobbyists like myself can easily get away with making up a desired zener value from putting two smaller value ones in series to add...

Whilst mere hobbyists like myself can easily get away with making up a desired zener value from putting two smaller value ones in series to add together their rated voltages, can such a dodge be employed by professional designers without losing face? I mean, in the case where there is no commercially available zener with precisely the desired breakdown voltage? Would a pro designer be op...


Dealing with mains power transients

Started by Sylvia Else in sci.electronics.design6 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.design10 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.design5 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.design1 year 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.design5 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


PNPs with high BV_EBO

Started by Phil Hobbs in sci.electronics.design4 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.design12 months 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.design5 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 ad hoc design continues to be useful

Started by Pimpom in sci.electronics.design2 years ago 13 replies

Have you ever designed and built something ad hoc (usually a simple one) but later found it useful for other applications? I have a few of...

Have you ever designed and built something ad hoc (usually a simple one) but later found it useful for other applications? I have a few of those. For example, I made an adjustable constant current source in the late '80s, specifically for sorting out my old collection of zener diodes. It supplies a regulated current that can be adjusted from 0.5 to 15mA at up to 50V. I fully expected ...


Simple circuit to flash an LED from RF

Started by amdx in sci.electronics.design2 months 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...


Zener noise / oscillations

Started by Robert Baer in sci.electronics.design10 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...


Turn signal flasher question

Started by amdx in sci.electronics.design2 years ago 8 replies

I have a turn signal flasher that I no longer hear. After both my kids commenting on my turn signal being on, I decided to do something about...

I have a turn signal flasher that I no longer hear. After both my kids commenting on my turn signal being on, I decided to do something about it. I tried just adding a mechanical piece to make it louder, it did but probably not enough. So I found a Sonolert and wired it to the output. However the output of the Flasher sets at 6V. I don't know why. I just put a zener in series and that...


Test Equipment.... The missing link

Started by Harry D in sci.electronics.design4 years ago 38 replies

Having spent over 50 years in electronic labs, designing and testing, I find myself trying to test zener diodes, FETs, LEDs, transistors and...

Having spent over 50 years in electronic labs, designing and testing, I find myself trying to test zener diodes, FETs, LEDs, transistors and many other semiconductor devices. I end up kluging parts to generate a current source with enough voltage compliance to suit my needs. After searching Amazon, eBay and most test equipment vendors, I find a lot of units but none that fit my needs. So...


5-volt tolerant CMOS

Started by John Larkin in sci.electronics.design9 years ago 38 replies

Lots of CMOS gates and such are tolerant of pin voltages above Vcc, typically rated for 7 volts max. Does anybody know what sort of input...

Lots of CMOS gates and such are tolerant of pin voltages above Vcc, typically rated for 7 volts max. Does anybody know what sort of input circuits are typically used? Does it behave like a zener? To ground? Some parts specify an allowed input curent in the pullup direction, some don't. I'm designing a really tiny board, and an opamp can potentially overdrive an analog mux, an FSA3157....


guard rings

Started by Anonymous in sci.electronics.design1 year ago 26 replies

Some schottky diodes have a PN junction in parallel, a "guard ring" that acts like a parallel zener to improve ESD specs, and may help with the...

Some schottky diodes have a PN junction in parallel, a "guard ring" that acts like a parallel zener to improve ESD specs, and may help with the fab somehow. That's OK, but at high currents the PN diode can turn on, and it's slow to turn off and can even act like a step-recovery diode. I wonder if there is a way to tell, from the data sheets, if there is a guard ring. VI curve? CV curve? ES...