Field strength meter -- diode

Started by mkr5000 in sci.electronics.design9 months ago 39 replies

Nothing could be simpler, an antenna, a coil and a 1N4148 diode but I'm seeing some schematics that have 2 diodes with one replacing the coil and...

Nothing could be simpler, an antenna, a coil and a 1N4148 diode but I'm seeing some schematics that have 2 diodes with one replacing the coil and the cathode connecting to the antenna. Now that I'm old and stupid can someone tell me what that diode is doing please? Thanks.


phemt diode

Started by John Larkin in sci.electronics.design1 year ago 10 replies

The late lamanted ATF-50189 phemt made an amazing diode. 1 amp and about 3 pF. I tried a MiniCircuits SAV-541 as a...

The late lamanted ATF-50189 phemt made an amazing diode. 1 amp and about 3 pF. I tried a MiniCircuits SAV-541 as a diode. https://www.dropbox.com/sh/0cgvrabjdichvu4/AAAGRgxUuWOEn0ULKFgjQK8da?dl=0 Cd is only about half a pF and Vf about 0.2. What's weird is that it's very noisy in the negative-drain "forward" conduction direction. It's the same at 20 MHz scope bandwidth, so it's not s...


Double balanced diode mixer question

Started by Anonymous in sci.electronics.design4 years ago 12 replies

Could some electronics guru here pleae help ? I want to simulate a double balanced diode mixer with a LO frequency of 50 MHz and RF frequency...

Could some electronics guru here pleae help ? I want to simulate a double balanced diode mixer with a LO frequency of 50 MHz and RF frequency of 100 MHz. Both LO and RF signal generators have a source resistance of 50.0 Ohms. The simplest Schottky diode model has a fixed resistance Rs, in series with a praallel Cj/Rj pair(junction capacitance/resistance). While Schottky diode SPICE mo...


Lambda diode gyrator, pt 2

Started by bitrex in sci.electronics.design3 years ago 15 replies

With a more appropriate op amp and better choice of operating point for the diode it looks like the lambda diode load really does provide a...

With a more appropriate op amp and better choice of operating point for the diode it looks like the lambda diode load really does provide a significant bandwidth improvement as compared to a resistive load for the gyrator in the high-pass configuration, about 4x, here: While preserving the low-frequency response


Hot-carrier diode substitute

Started by garyr in sci.electronics.design9 years ago 12 replies

I want to make a simple rectifier for an RF signal, frequency less than 10 MHz. The schematic below (view with fixed font) is from an...

I want to make a simple rectifier for an RF signal, frequency less than 10 MHz. The schematic below (view with fixed font) is from an article describing a circuit useable with much higher frequencies and used a hot-carrier diode (1N5711). For relative low frequencies would a general purpose diode such as a 1N4148 be adequate? If a hot-carrier would be necessary I have a problem because I do...


Max current for a JFET connected as diode

Started by neo5...@gmail.com in sci.electronics.design6 months ago 37 replies

Hi; I've been using N channel Jfets connected as diodes for input protection for a long time. Everything seems to just work. Recently an...

Hi; I've been using N channel Jfets connected as diodes for input protection for a long time. Everything seems to just work. Recently an application came up where the low leakage of a diode connected FET would be useful but when forward biased it could pass tens to a few hundred mA. Does anyone know what characteristic of a JFET would define the max current through the Diode connec


Sampler diodes with more barrier height?

Started by Joerg in sci.electronics.design9 years ago 100 replies

Folks, After John Larkin sent me SMS7621 Schottky RF diodes I played around with them in the lab. While they perform nicely at room...

Folks, After John Larkin sent me SMS7621 Schottky RF diodes I played around with them in the lab. While they perform nicely at room temperature everything goes to pots at a slightly elevated temperature. At ballpark 50C the leakage current is already painfully high for use as a sampler diode. Question: Is there a fast RF diode or sampling diode in a reasonable cost range (low single-dig...


Next: The tunnel diode oscillator.

Started by Jan Panteltje in sci.electronics.design9 years ago 33 replies

Next: The tunnel diode oscillator. Given an LC wit some Q (read damping), if we can neutralize that R, would it start swinging all by...

Next: The tunnel diode oscillator. Given an LC wit some Q (read damping), if we can neutralize that R, would it start swinging all by itself? Well how do you neutralize a resistor? Simple: put a negative resistor in series or parallel with it. Mr Esaki invented the tunnel diode many years ago, it has, at some point, a negative slope in its I versus U curve. So use a properly biased...


JFET used as a diode

Started by Piotr Wyderski in sci.electronics.design4 years ago 39 replies

I need a low current, low voltage and extremely low leakage diode. The gate junction of MMBFJ202 seems extremely well-suited for the job. The...

I need a low current, low voltage and extremely low leakage diode. The gate junction of MMBFJ202 seems extremely well-suited for the job. The datasheet says its absolute maximum gate current is 50mA. Can I operate it reliably at 20mA for years? I mean, would there be any relevant degradation mechanism or is this junction an ordinary diode and I shouldn't worry about it? Best regards, Pio...


where to get NO diode embedded flybacks?

Started by Al Butterworth in sci.electronics.design3 years ago 8 replies

Looking for a source for getting NO diode embedded flybacks to be able to run multiplier circuits, etc. I am in the US. Thank you. AB

Looking for a source for getting NO diode embedded flybacks to be able to run multiplier circuits, etc. I am in the US. Thank you. AB


Diode laser FM/AM modulation

Started by George Herold in sci.electronics.design6 years ago 10 replies

So we modulate the light from a diode laser by wiggling the diode current. This has two effects, the most obvious is that it changes the...

So we modulate the light from a diode laser by wiggling the diode current. This has two effects, the most obvious is that it changes the amplitude of the light. (AM) Less obvious (though I think more dominant in changing the frequency.) is that changing the laser current has two other effects on the frequency. At low frequencies (


Improving my best diode detector

Started by amdx in sci.electronics.design5 years ago 42 replies

Hi Guys, I have three Diode Detectors built as the Figure 4 schematic in this article, using different number diodes. >...

Hi Guys, I have three Diode Detectors built as the Figure 4 schematic in this article, using different number diodes. > https://www.rf-microwave.com/uploads/diodes/a_temperature_compensated_linear_diode_detector.pdf I used Bat62, 1n5711 and some unknown germanium diodes I pulled of of some old pcbs. The best is the unknown germainums, which are probably 1N34A diodes. I have som


Diode Array

Started by Anonymous in sci.electronics.design5 years ago 10 replies

I'm looking for a replacement for the CA3039 diode array, which has been successfully used in a precision demodulator circuit operating up to 1...

I'm looking for a replacement for the CA3039 diode array, which has been successfully used in a precision demodulator circuit operating up to 1 MHz. The part has been obsoleted by Intersil. The important characteristics are low leakage current (less than 0.1 nA at 25C with 1 V reverse bias) and close matching of forward voltage drops. Also, the forward voltage drop with 1 nA or le


Diode (LED) parameters in LTSpice

Started by John S in sci.electronics.design5 years ago 3 replies

This is the model I'm using: .model LXHL-BW02 D(Is=4.5e-20 Rs=.85 N=2.6 Cjo=1.18n Xti=200 Iave=400mA Vpk=5 mfg=Lumileds type=LED) It is...

This is the model I'm using: .model LXHL-BW02 D(Is=4.5e-20 Rs=.85 N=2.6 Cjo=1.18n Xti=200 Iave=400mA Vpk=5 mfg=Lumileds type=LED) It is the closest selection of Vf to the diode I'm going to use. However it is a bit higher than the spec sheet. How do I adjust the parameters above to get a lower Vf? Thanks, Guys. JohnS


Diode -- pick and place

Started by mkr5000 in sci.electronics.design1 year ago 44 replies

When I place an SMD diode in my pcb art top layer, (SOD123) and it's rotated 90 degrees -- is the anode on the right or left? (and obviously...

When I place an SMD diode in my pcb art top layer, (SOD123) and it's rotated 90 degrees -- is the anode on the right or left? (and obviously the opposite for 270). I'm asking because I still don't get the silkscreen layer symbol for the part but maybe there is a standard based on rotation and the screen symbol doesn't matter? Like even if I had a generic 1206 or something there, they would...


need really bad diode

Started by John Larkin in sci.electronics.design2 weeks ago 22 replies

I want lots of voltage drop at 100 mA or so. A high voltage fast-recovery diode, like ES1G, might work. I suppose I could just put two...

I want lots of voltage drop at 100 mA or so. A high voltage fast-recovery diode, like ES1G, might work. I suppose I could just put two ES1Gs in series, but that's not sporting. MMBD5004S is two wimpy diodes in series, in SOT-23. That would drop about 2 volts at 100 mA! This is a supply sequencing dilemma with the LT6803. A long story.


Series Resistor and TVS diode placement

Started by mahen in sci.electronics.design9 years ago 46 replies

If I have to put ESD diode and current limiting series resistor to protect the IO pin of MCU from ESD and over current, which is the suggested...

If I have to put ESD diode and current limiting series resistor to protect the IO pin of MCU from ESD and over current, which is the suggested way? MCU Pin -------------- Series R -- TVS to GND -- Connector or MCU Pin -------------- TVS to GND -- Series R-- Connector With the 2nd option, doesn't the R limit the surge into TVS needing only lower wattage ESD diode compared to 1st option?...


photodiode voltage

Started by Anonymous in sci.electronics.design2 years ago 30 replies

https://optodiode.com/pdf/SXUV5DS.pdf That's a common trick in the exotic photodiode biz. The part has guaranteed 5 volt reverse. Typ...

https://optodiode.com/pdf/SXUV5DS.pdf That's a common trick in the exotic photodiode biz. The part has guaranteed 5 volt reverse. Typ breakdown is 20. It's tested for speed at 15. The graphs go to 25. What's a boy to do? I did one EUV diode preamp (not this diode) where I allowed the system to program bias up to -75 volts. The customer made me limit the voltage to -10, by means of...


PIN diode appnote

Started by Anonymous in sci.electronics.design10 months ago 6 replies

https://www.microsemi.com/document-portal/doc_view/134814-micronote-701-pin-diode-fundamentals Of course, given that this is an RF appnote,...

https://www.microsemi.com/document-portal/doc_view/134814-micronote-701-pin-diode-fundamentals Of course, given that this is an RF appnote, it's wrong. Interesting pattern: clumsy font changes are flags for errors. -- Father Brown's figure remained quite dark and still; but in that instant he had lost his head. His head was always most valuable when he had lost it. ...


1N34A Germanium Diode finally found!!

Started by Anonymous in sci.electronics.design9 years ago 49 replies

I finally found some 1n34a diodes and one of my new favorite sites! http://www.bgmicro.com/1n34a-germanium-diode.aspx

I finally found some 1n34a diodes and one of my new favorite sites! http://www.bgmicro.com/1n34a-germanium-diode.aspx