To Phill Hobbs

Started by Anonymous in sci.electronics.design6 years ago 26 replies

Hi ! I have been reading this article from you http://www.electrooptical.net/www/canceller/shotnoise_opn.pdf In pp. 21 fig.4 I did not...

Hi ! I have been reading this article from you http://www.electrooptical.net/www/canceller/shotnoise_opn.pdf In pp. 21 fig.4 I did not understand prunfundly why this a noise canceler, Are you sure you could eliminate the two diode noises just because you make the ratio in this equ. Va2 = -Log((i_sample/i_signal) - 1). I remember independent noises sources are not correlated ; T


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...


Improved Diode Recovery Model

Started by Tim Williams in sci.electronics.design4 years ago 7 replies

https://docs.google.com/viewer?a=v&pid=sites&srcid=ZGVmYXVsdGRvbWFpbnxyc3RldmVzY290dHxneDo1NjQ1Z TI1ZTY2MWFiM2Yz This had been discussed some...

https://docs.google.com/viewer?a=v&pid=sites&srcid=ZGVmYXVsdGRvbWFpbnxyc3RldmVzY290dHxneDo1NjQ1Z TI1ZTY2MWFiM2Yz This had been discussed some time ago. There was a lot of bragging about being able to create a model, but nothing came of it. Fortunately, this guy had beaten us to the punch, and released this paper publically. The design with multiple time constants makes me think of appro


speaking of substrate diodes...

Started by Anonymous in sci.electronics.design3 months ago 2 replies

leads to this one... https://www.dropbox.com/s/cgaxalnn3hhf315/RRIO_Logamp.jpg?raw=1 where we use the substrate diode of a RRIO opamp as a...

leads to this one... https://www.dropbox.com/s/cgaxalnn3hhf315/RRIO_Logamp.jpg?raw=1 where we use the substrate diode of a RRIO opamp as a logarithmic current-to-voltage converter. There are better ways to do this, but maybe none so cute. -- Father Brown's figure remained quite dark and still; but in that instant he had lost his head. His head was always most valuable whe...


fast diodes gone

Started by John Larkin in sci.electronics.design2 weeks ago 7 replies

There used to be a bunch of low-barrier schottky diodes with Cjo < < 1 pF and equivalent series resistance < 5 ohms, SC79...

There used to be a bunch of low-barrier schottky diodes with Cjo < < 1 pF and equivalent series resistance < 5 ohms, SC79 package. BAT63 SMS1546 SMS3927 but they seem to be all gone. Strange. SMS3922 is available, with C=0.7 pF and Rs = 9 typ. Maybe I can use a small phemt as a diode. It seems as if quantity-billion ICs keep killing off fast discrete parts. -- If a man wil


Finding LTspice Models

Started by Ricky C in sci.electronics.design2 years ago 13 replies

LTspice is a nice program... well, it's ok in many respects and great in others. But it can be a PITA to find models for. I'm looking at a...

LTspice is a nice program... well, it's ok in many respects and great in others. But it can be a PITA to find models for. I'm looking at a number of possible parts to use in a new design but many of them have no spice models. I'm not so worried about finding an accurate LED model. But I'm using a Schottky diode to prevent back feeding of power through a regulator and I need a


guard ring?

Started by John Larkin in sci.electronics.design3 years ago 39 replies

I'm still iterating on my high-voltage pulse generator. Rev C looks very good. I've been pushing it up voltage and frequency (like,...

I'm still iterating on my high-voltage pulse generator. Rev C looks very good. I've been pushing it up voltage and frequency (like, 1200 volts and 4 MHz) and seeing what parts fry, and working on them. I have a dpak schottky diode in a sort of snubber place. According to Spice, it shouldn't get too hot, and it's soldered to all sorts of copper pours and thermal vias and stuff. It's an S...


BJTs as ultra low leakage protection diodes

Started by Ebrahim in sci.electronics.design13 years ago 51 replies

Hello, I want is there anyone that has used a BJT instead of ultra low leakage diode(

Hello, I want is there anyone that has used a BJT instead of ultra low leakage diode(


How to select a good ultrasonic transducer ?

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

Could some electronics guru please help ? I happened to come across some sample ultrasonic sound generator design/schematic(s), which...

Could some electronics guru please help ? I happened to come across some sample ultrasonic sound generator design/schematic(s), which include an 'ultrasonic transducer'. What exactly is this? Some sort of special loudspeaker for the ultrasonic frequency range ? Specifically, if one where to buy one of these, what would one ask for -- i.e., if I want to buy a common rectifier diode, I ...


Boost converter wisdom

Started by Phil Hobbs in sci.electronics.design3 years ago 37 replies

Hi, all, I'm doing a miniaturized version of my low noise diode laser controller for a big biomed customer. It's supposed to replace an...

Hi, all, I'm doing a miniaturized version of my low noise diode laser controller for a big biomed customer. It's supposed to replace an existing unit for retrofitting, as well as being designed in to their new products. The wrinkle is that it has to run off a single +5V supply instead of our usual +24V. Sooooo, it needs a boost converter. To reduce the dissipation in the TEC drive...


Input of unpowered OpAmp

Started by panfilero in sci.electronics.design8 years ago 7 replies

I had a voltage divider which was suppose to drop down a voltage to 3V conn= ected to the input of an OpAmp. And it worked fine. But I noticed,...

I had a voltage divider which was suppose to drop down a voltage to 3V conn= ected to the input of an OpAmp. And it worked fine. But I noticed, when I= powered off the OpAmp, that 3V dropped down to 1.7V, I wasn't expecting th= is. What do you think would cause this? My guess is some input protection = circuitry, maybe a couple diode drops or something?


Teaching the young.

Started by Jamie in sci.electronics.design10 years ago 8 replies

A few years ago I used to visit boy scott meetings and introduce them to basic concepts of computer programming using Pascal and basic...

A few years ago I used to visit boy scott meetings and introduce them to basic concepts of computer programming using Pascal and basic electronics. I still remember one little boy asking me if I could explain how a "Reverberating Diode" worked! I tried like hell not to laugh but I knew that his father or some one in the family must of been some Electronics/Electrician tech and set me...


1965 Allied Catalog

Started by John Larkin in sci.electronics.design5 years ago 45 replies

Ungar soldering iron 98 cents KG2000 oscilloscope kit $199.50 (all tubes, 5 MC, triggered sweep, DC coupled... I had one) 1%...

Ungar soldering iron 98 cents KG2000 oscilloscope kit $199.50 (all tubes, 5 MC, triggered sweep, DC coupled... I had one) 1% axial resistor 54 cents 10% carbon comp resistor 13 cents 1N914 diode $1.50 2N2222A $6.75 12AX7A $1.28 The dollar-value adjustment is about 8:1. So the cost of gumdrop parts is now hundreds of times less than it was then. My all...


Troubleshooting 'shorted' power rails

Started by Anonymous in sci.electronics.design3 years ago 46 replies

I had two cases in a row recently of many-layer power-planed boards with power supplies that wouldn't come up above a diode drop, and I was able...

I had two cases in a row recently of many-layer power-planed boards with power supplies that wouldn't come up above a diode drop, and I was able to use a trick devised for the first one to solve the problem on the second one, too -- I set a current-limited supply to ~30mA & left the board to stabilize thermally. I then looked for the 'hot' parts with an IR thermometer. Worked like a charm...


New Switching Converter Topology?

Started by Tim Williams in sci.electronics.design4 years ago 32 replies

Does this... exist? I mean, has it been named, or enumerated...

Does this... exist? I mean, has it been named, or enumerated anywhere? https://www.seventransistorlabs.com/Images/Bidirectional_Buck.png Sort of like a Cuk, but swapping the capacitor and switch. Could be used for low ripple buck (drop D1 and Q2), a kind of extended-winding boost (change D1 to transistor, Q2 to diode, drop Q1 and D2), equalizing source/load (note that switching Q1+Q2...


Little 1:10 audio transformer as HV transformer

Started by Jan Panteltje in sci.electronics.design10 years ago 125 replies

Little 1:10 audio transformer as HV transformer Thse are small transformers with a ferrite core, specified as 6H secundair, and turns ratio...

Little 1:10 audio transformer as HV transformer Thse are small transformers with a ferrite core, specified as 6H secundair, and turns ratio 1:10. (conrad nr 516260). The idea was to make 400 V from 5 V with a PIC. That requires at least 40V peak primary. I tried some BC547B, but changed to a IRLZ434N MOSFET, as this one has the reverse diode for free, I tried many frequencies and pulse w...


8051F020 series, 5V tolerant input schematic?

Started by Joerg in sci.electronics.design9 years ago 89 replies

Folks, Got a Silicon Labs 8051Fxxx with 5V-tolerant ports. In the abs max it says 5.8V is the limit. Well, if one uses the typical diode...

Folks, Got a Silicon Labs 8051Fxxx with 5V-tolerant ports. In the abs max it says 5.8V is the limit. Well, if one uses the typical diode against the 5V rail it could go slightly above 6V in case of a really big jolt. Since this 8051 does not have a 5V supply but just VDD (which hangs on 3.3V in this case) there can't be any parasitic substrate diodes dumping into a rail. Does anyone kno...


Meat thermometer, what kind of sensor is in there?

Started by Joerg in sci.electronics.design5 years ago 63 replies

Just had a wireless meat thermometer suddenly fail in the middle of a brewing session (Belgian Tripel, can't wait ...) [*]. The indicated temp...

Just had a wireless meat thermometer suddenly fail in the middle of a brewing session (Belgian Tripel, can't wait ...) [*]. The indicated temp shot up about 50F. Resetting the uC, display and so on won't help. It's going to be replaced under warranty but being the curios one I measured then sensor. It reads about 45kohms in one direction and about 70kohms in the other. No diode slope to ...


How about it? Experiments of the third kind , take 999999.

Started by Jan Panteltje in sci.electronics.design10 years ago 59 replies

This is an idea for an experiment I may or may not do. The background: There have been reported seasonal variations in radioactive decay in the...

This is an idea for an experiment I may or may not do. The background: There have been reported seasonal variations in radioactive decay in the past. Now If I took a simple tritium light, and a good quality photo-diode, put both in a light proof box, and logged that with a 10 bit PIC ADC with a decent Vref for say a year to FLASH, say 1 sample / hour, run the whole thing of some battery. ...


How about it? Experiments of the third kind , take 999999.

Started by Jan Panteltje in sci.electronics.design10 years ago 5 replies

I wrote: > This is an idea for an experiment I may or may not do. > The background: > There have been reported seasonal variations in...

I wrote: > This is an idea for an experiment I may or may not do. > The background: > There have been reported seasonal variations in radioactive decay in the past. > > Now If I took a simple tritium light, and a good quality photo-diode, > put both in a light proof box, > and logged that with a 10 bit PIC ADC with a decent Vref for say a year > to FLASH, say 1 sample / hour, run the whole thing