Little thermal thing

Started by George Herold in sci.electronics.design3 years ago 7 replies

A 0.25" x 1.3 " pcb holds a sensor, heater (300 ohm, 1206 or bigger) and diode temp. sensor. I first made it with a common ground for the...

A 0.25" x 1.3 " pcb holds a sensor, heater (300 ohm, 1206 or bigger) and diode temp. sensor. I first made it with a common ground for the heater and diode, but there was to much offset from the heater current* and I had to add a third wire to sense local ground for the diode. Which worked great. About a 2 sec thermal time constant. When I cut the ground plane (razor blade on thermals) ...


Diode reverse breakdown voltage in SPICE

Started by Daku in sci.electronics.design10 years ago 1 reply

Could some electronics guru please clarify this issue a bit ? A typical SPICE model for a diode lists the BV (breakdown voltage) and IBV(reverse...

Could some electronics guru please clarify this issue a bit ? A typical SPICE model for a diode lists the BV (breakdown voltage) and IBV(reverse breakdown current). How is the reverse breakdown voltage specified ? This would be important, e.g., for a power diode. Thanks in advance for your help.


A more sensitive RF diode?

Started by Jan Panteltje in sci.electronics.design2 years ago 24 replies

A more sensitive RF diode? https://www.fujitsu.com/global/about/resources/news/press-releases/2019/0924-01.html

A more sensitive RF diode? https://www.fujitsu.com/global/about/resources/news/press-releases/2019/0924-01.html


LT Spice diode model

Started by John Larkin in sci.electronics.design9 years ago 1 reply

Hi, I'm adding a diode model, SMS7621-079, to the LT Spice standard.dio file. My diode data sheet shows Spice parameter Cjo = 0.1 pF, but...

Hi, I'm adding a diode model, SMS7621-079, to the LT Spice standard.dio file. My diode data sheet shows Spice parameter Cjo = 0.1 pF, but the parts have a typical capacitance of 0.22 pF. I assume the extra capacitance is the package, which wouldn't behave like Cjo. I don't see an obvious place, in the model script, for the package c. There are some "sidewall" params, but I don't kno...


Does a diode in the Vcc line disable clamp diodes to Vcc

Started by Bill in sci.electronics.design9 years ago 18 replies

I have a case where I want to put about 20 microamps into an AVR at 12v. AVRs have clamp diodes to both ground and Vcc on their digital...

I have a case where I want to put about 20 microamps into an AVR at 12v. AVRs have clamp diodes to both ground and Vcc on their digital inputs. It seems to me that a diode inline with the Vcc supply would disable the internal clamp diodes of the chip. Am I correct on this or is the internal circuitry fancier than a simple clamp diode. Thanks, Bill


Si-C MOSFET body diode

Started by Harry D in sci.electronics.design7 years ago 5 replies

So I am testing a C2M002512D body diode, see attached. I have two test setups at 25C with different results. 1, Short G to S and apply -1.0ma...

So I am testing a C2M002512D body diode, see attached. I have two test setups at 25C with different results. 1, Short G to S and apply -1.0ma of current from D to S; measure Vds = -1.07V 2, Apply G=-5V, S=0 and apply -1.0mA of current D to S; measure Vds= -2.40V Look at attached spec, sheet #4. Looks like Vgs can modulate the body diode. Cheers, HarryD


Zener diode below-threshold reverse current

Started by Tim Wescott in sci.electronics.design5 years ago 271 replies

I know the theory, more or less. In practice, what's the reverse current through a zener diode at levels well below the breakdown voltage? ...

I know the theory, more or less. In practice, what's the reverse current through a zener diode at levels well below the breakdown voltage? I've got a circuit where I'm feeding a 12V linear regulator with a 25V line. It would be handy to put a zener diode in there so that when the 25V line drops to 4V the current into the regulator drops to tens of microamps. I'm wondering if a series...


150 ps TDR sampler--dead bug!

Started by Phil Hobbs in sci.electronics.design5 years ago 4 replies

ChesterW and I have spent the last couple of days doing a dead-bug proto of a single-diode TDR front end I designed for a mutual client. It...

ChesterW and I have spent the last couple of days doing a dead-bug proto of a single-diode TDR front end I designed for a mutual client. It uses all SOT23, SC-70, 0603, and a super small (0402ish) sampling diode. It includes the TX pulse generator, sample pulse generator, sampling diode, and a ~100~MHz bandwidth buffer and voltage amplifier Connectors are MMCX to minimize pigtail inducta...


Semiconductor lasers

Started by Aleksandar Kuktin in sci.electronics.design6 years ago 13 replies

I tore up a computer mouse to get my grubby little paws on a laser. Only.. I'm not sure it's a laser. Apart from testing the output for...

I tore up a computer mouse to get my grubby little paws on a laser. Only.. I'm not sure it's a laser. Apart from testing the output for coherence, is there a way to tell a laser diode from a light-emitting diode? Other than that, how do you drive these things? Is there some Internet- accessible resource where this is explained? Usually, I begin my crawl with Wikipedia, but on the subj...


PS12015 power supply, from Velleman and others, LM723 based

Started by Sonnich Jensen in sci.electronics.design5 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...


where to get NO diode embedded flybacks?

Started by Al Butterworth in sci.electronics.design2 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


wimpy diode

Started by John Larkin in sci.electronics.design6 years ago 41 replies

I need a wimpy diode, with lots of forward drop at a few mA, to bias up an e-phemt. Thought I'd try a small-geometry NPN...

I need a wimpy diode, with lots of forward drop at a few mA, to bias up an e-phemt. Thought I'd try a small-geometry NPN transistor. https://dl.dropboxusercontent.com/u/53724080/Parts/Transistors/BCX70_as_Diode.JPG Looks good. The b-e and b-c junctions look symmetric. The middle config looks like the classic 60 mV/decade-current, and the others are maybe a little ohmic. We pay 2.4 cen...


Diode laser FM/AM modulation

Started by George Herold in sci.electronics.design5 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 (


Inductor current can't be suddenly cutoff if no freewheel diode is attached

Started by Patrick Chung in sci.electronics.design8 years ago 49 replies

Inductor current can't be suddenly cutoff if no freewheel diode is attached. New tutorial...

Inductor current can't be suddenly cutoff if no freewheel diode is attached. New tutorial is ready http://www.cirvirlab.com/index.php/tutorials/105-r-l-circuit-with-mosfet-as-switch-and-freewheel -diode.html and online simulation http://www.cirvirlab.com/simulation/r-l_circuit_with_mosfet_as_switch_and_freewheel_diode.php


capacitor nonlinearity again

Started by John Larkin in sci.electronics.design9 years ago 31 replies

Does anybody have an LT Spice example that models the C-V dependence of a ceramic cap? I was thinking about the parametric frequency divider...

Does anybody have an LT Spice example that models the C-V dependence of a ceramic cap? I was thinking about the parametric frequency divider that I did with a diode, and it occurs to me that a capacitor's c (probably) falls off symmetrically with +- voltage, but a diode is asymmetric. So the capacitor based parametric divider is different. It might be fun to play with that. -- Jo...


Art of Electronics (1st Ed) ex 1.28 - am I right

Started by Anonymous in sci.electronics.design6 years ago 4 replies

Hello, Technician's Apprentice Here, I was given this book as a source to expand my knowledge, and not being able to flip to the back and verify...

Hello, Technician's Apprentice Here, I was given this book as a source to expand my knowledge, and not being able to flip to the back and verify my answers is troubling but not impassable. Please help me check my grasp on the material. The subject is Diode gates. The sample is an AC fed +15v DC power supply through the anode of a diode to a +12V to +15V electronic clock with the cathode comm...


Schottky diode

Started by Michael in sci.electronics.design6 years ago 16 replies

What is Schottky diode turn on time? I know that it is very low (have always been low enough for me). Until now that is... I am looking for more...

What is Schottky diode turn on time? I know that it is very low (have always been low enough for me). Until now that is... I am looking for more quantitative information Reason for this posting: Prototype with MBRX140-TP diodes behaves differently from the product board with 1N5819HW. The diodes are used to keep inductive load driver output "contained" between power rail and GND. Both boards ...


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.design4 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.design4 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