Diode -- pick and place

Started by mkr5000 in sci.electronics.design8 months 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...


Car alternator failure -- twice!

Started by Sparky in sci.electronics.design7 years ago 26 replies

Last year the alternator on my Toyota cooked the stator windings. I didn?t look any further and replaced it with a rebuilt alternator &...

Last year the alternator on my Toyota cooked the stator windings. I didn?t look any further and replaced it with a rebuilt alternator & regulator from the local parts supplier. Now (7 or 8 months later) the replacement has failed in the same mode. I?m suspicious. Also confused: If a diode opens there wouldn?t be an increased load on the stator windings. If a diode shorts, there also...


paralleling relay coils

Started by Anonymous in sci.electronics.design8 years ago 80 replies

I am connecting five 12V relay coils in parallel to switch five different loads. Is it necessary to have fly-back diode for each relay coil or...

I am connecting five 12V relay coils in parallel to switch five different loads. Is it necessary to have fly-back diode for each relay coil or just one 1N400x diode in parallel is sufficient? Each coil is 300 ohms. -bhavj


Temperature compensating diode drops

Started by Phil Hobbs in sci.electronics.design5 years ago 56 replies

Hi, all, I'm designing a diode laser controller board for a customer in Scandinavia. It has a sub-Poissonian adjustable current supply, a...

Hi, all, I'm designing a diode laser controller board for a customer in Scandinavia. It has a sub-Poissonian adjustable current supply, a resistor-linearized thermistor temperature sensor, and of course a thermoelectric cooler driver. The TEC requires different current limits in different quadrants. (A TEC is actually a four-quadrant device since it generates electrical power fro...


Obscure vacuum tube question

Started by bitrex in sci.electronics.design3 years ago 9 replies

6 volt filament, 9 pin miniature tubes that have a pentode and single diode in the same envelope, that have a modest heater current...

6 volt filament, 9 pin miniature tubes that have a pentode and single diode in the same envelope, that have a modest heater current requirement (500mA or less.) With a separate cathode and anode for the diode, not sharing the other tube's cathode as many did. Obscure, I know. :) I looked through my GE "Essential Characteristics" book and only found two. 6HJ8. 6AS8. Huh. I thought the...


Zener diode modeling

Started by Robert Baer in sci.electronics.design10 years ago 36 replies

Say one takes an E-B junction of a transistor or other diode and measures the (reverse) breakdown voltage over a wide range of currents...

Say one takes an E-B junction of a transistor or other diode and measures the (reverse) breakdown voltage over a wide range of currents (say 5nA to 5mA), and assume there is no point or range where one sees characteristics of negative resistance or of oscillation. Also say that voltage is about 9 volts. Q: is that zener or avalanche breakdown? Q: how does one make a SPICE mode...


Series Resistor and TVS diode placement

Started by mahen in sci.electronics.design8 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?...


More ESD-diode leakage paranoia!

Started by Tim Williams in sci.electronics.design5 years ago 9 replies

Saw this and had to share: http://www.eevblog.com/forum/projects/da112s1-diode-array-what's-occurring-weirdness/msg1196845/ #msg1196845 I've...

Saw this and had to share: http://www.eevblog.com/forum/projects/da112s1-diode-array-what's-occurring-weirdness/msg1196845/ #msg1196845 I've measured similar leakage between 74HC logic input pins. Tim -- Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design Website: http://seventransistorlabs.com


photodiode voltage

Started by Anonymous in sci.electronics.design1 year 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...


Lumped parameter model of pn-junction diode

Started by Daku in sci.electronics.design10 years ago 3 replies

Could some electronics guru please point me to a lumped parameter model of a pn-junction diode ? Does such a model exist ? Any hints,...

Could some electronics guru please point me to a lumped parameter model of a pn-junction diode ? Does such a model exist ? Any hints, suggestions would be greatly appreciated.


PIN diode appnote

Started by Anonymous in sci.electronics.design2 weeks ago 4 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. ...


o/p of boost converter if the regulator is shutdown

Started by Anonymous in sci.electronics.design8 years ago 5 replies

I am usiing LMR64010 to convert 5V to 12V. Load current is approx 150ma. Th= e schematic is as per the application circuit in the datasheet. If I...

I am usiing LMR64010 to convert 5V to 12V. Load current is approx 150ma. Th= e schematic is as per the application circuit in the datasheet. If I pull t= he shutdown pin to ground the o/p is approx 4.6V. Looking at the circuit th= ere is an i/p to o/p path through the inductor and diode giving me 5V minus= diode drop during shut down.=20 Is it normal for boost converters? is there a simple...


The linear Diode Detector

Started by amdx in sci.electronics.design5 years ago 89 replies

Hi guys, I'm now moving to the diode detector that I want linear over a 10 to 1 range. Say 0.5v input to 5v input or .75v input to 7.5v...

Hi guys, I'm now moving to the diode detector that I want linear over a 10 to 1 range. Say 0.5v input to 5v input or .75v input to 7.5v input. As it stands my amp has a 470 ohm output impedance, I will adjust as needed. I found this article, that I think does what I want. However it is tested a 900Mhz, I'm happy to get to 10MHz. Do I scale the capacitor scale with frequency? (.04...


1N34A Germanium Diode finally found!!

Started by Anonymous in sci.electronics.design8 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


Thyrectors (TVS Diode)

Started by Warren in sci.electronics.design4 years ago 3 replies

http://www.edn.com/electronics-blogs/tales-from-the-cube/4327133/Align-up-The-case-of-the-out-of-sync-synchro-amps This brings back memories of...

http://www.edn.com/electronics-blogs/tales-from-the-cube/4327133/Align-up-The-case-of-the-out-of-sync-synchro-amps This brings back memories of my current loop teletype days (driven by an 8008). Having learned that I needed a reversed biased diode in my relay driving circuit, I then encountered the relay turn off delay problem. At that time, I ended up with some sort of RC circuit t


Ideal Diodes

Started by Jenkins in sci.electronics.design10 years ago 19 replies

For low voltage(

For low voltage(


Favorite part, Low VF diode, low leakage

Started by Klaus Kragelund in sci.electronics.design9 years ago 8 replies

Hi I am working on a forward converter and are into optimizing the diode losses. Sofar the BAT720 has proven fairly good, but would like to...

Hi I am working on a forward converter and are into optimizing the diode losses. Sofar the BAT720 has proven fairly good, but would like to get even lower losses. So, when the PIV is 20V, I found the DFLS130: http://www.diodes.com/datasheets/ds30445.pdf Has really low VF, but one gain seldom comes with a penalty. It has high leakage current at elevated temperatures. Anyone got a...


Typical capacitance of a bigger laser diode?

Started by Joerg in sci.electronics.design10 years ago 41 replies

Folks, Looked through numerous datasheets in the 100-200mW power range from Sanyo, Sony, OSI, Ondax and so on ... nada. My experience when...

Folks, Looked through numerous datasheets in the 100-200mW power range from Sanyo, Sony, OSI, Ondax and so on ... nada. My experience when calling is that there is no further info available. So, does anyone know what the typical capacitance of an IR laser diode in that power range is? A SPICE model would be even better. Reason I ask is that we have to pulse-modulate the heck out of one, ...


Diode on light load keeps failing

Started by Pimpom in sci.electronics.design4 years ago 36 replies

This question arises from a repair work I'm doing on a friend's plasma TV - a Panasonic TH-P42X30T. The rectifier for the 5V standby supply...

This question arises from a repair work I'm doing on a friend's plasma TV - a Panasonic TH-P42X30T. The rectifier for the 5V standby supply failed short. The rectifier is a B3100, a schottky diode rated at 3A & 100V. The service manual I downloaded omits a detailed schematic of the power supply board but at least the load currents of the various voltages are printed on the board. The ...


guard rings

Started by Anonymous in sci.electronics.design8 months 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...