Cooling and insulating fluid

Started by Robert Baer in sci.electronics.design8 years ago 71 replies

I would like maximum thermal transfer (due to thermal circulation in an enclosed tube) as well as good electrical insulation to (say) 25KV...

I would like maximum thermal transfer (due to thermal circulation in an enclosed tube) as well as good electrical insulation to (say) 25KV minimum. The tube is 1.5" diameter OD by about 6" long. Two PCBs will be stacked end-to-end, and centrally located; their dimension is 1.17 wide by 2.850 tall. There are 168 zeners on each board for about 25KV zener regulation; at 1mA t...


Test Equipment.... The missing link

Started by Harry D in sci.electronics.design2 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...


TLV431 maximum ratings

Started by bitrex in sci.electronics.design1 year ago 9 replies

The TLV431 spec as an expample, shows a maximum Ika current rating of +/- 20mA does that mean it can be run "forward biased" as well as...

The TLV431 spec as an expample, shows a maximum Ika current rating of +/- 20mA does that mean it can be run "forward biased" as well as reversed in the usual Zener-like direction, and source current as well as sink it? like if you wanted to press it into service in some situation as an analog to a one-input low voltage op-amp with a


5-volt tolerant CMOS

Started by John Larkin in sci.electronics.design7 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....


AC Cap Dropper DC Power Supply

Started by Jim Thompson in sci.electronics.design8 years ago 114 replies

AC Cap Dropper DC Power Supply Anyone know of a clever way to regulate other than the typical brute-force zener clamp? ...

AC Cap Dropper DC Power Supply Anyone know of a clever way to regulate other than the typical brute-force zener clamp? ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Pho...


NPN protective zener

Started by Winfield Hill in sci.electronics.design1 year ago 94 replies

NPN signal transistors make pretty good low-capacitance signal and MOSFET-gate protection zeners, etc. For example, the emitter-base...

NPN signal transistors make pretty good low-capacitance signal and MOSFET-gate protection zeners, etc. For example, the emitter-base junction of the common 2N3904 breaks down near 7.25 volts, and has 6 to 7pF of capacitance at 0V, drops to about 3.7pF at 5 volts. Has anybody taken pulsed high-current voltage-drop measurements on these guys? -- Thanks, - Win


Dumb question on noise source

Started by David Eather in sci.electronics.design3 years ago 15 replies

My test gear (along with most of my brain) have been packed away, so I can only ask this as a question rather than lash it up and know. I...

My test gear (along with most of my brain) have been packed away, so I can only ask this as a question rather than lash it up and know. I have a +/- 5v source and a 6.8v zener diode as a noise source. I'm expecting about 0.3mV noise. My question is: will I get more noise by biasing with a resistor (about 3.3k) or biasing with a constant current source. TIA -- I look forward t...


Over Voltage Protection Crowbar Circuit

Started by panfilero in sci.electronics.design8 years ago 73 replies

I'm needing an over-voltage protection circuit to put at the output of a switching regulator that takes in 100V input and drops it to 24V... I'd...

I'm needing an over-voltage protection circuit to put at the output of a switching regulator that takes in 100V input and drops it to 24V... I'd like to protect the output from going over 28V. Here's the 3 options I was considering: For all the options the point is to blow my 5A fast acting fuse that's at the input, so I'm trying to decide on a way to short my output 1. A Zener - I'm think...


Using NE2 bulbs as voltage regulators

Started by Geoffrey S. Mendelson in sci.electronics.design5 years ago 33 replies

I am building an experimental radiation detector. Being an experiment, I want to avoid buying anything for it. Sort of a junkbox project to...

I am building an experimental radiation detector. Being an experiment, I want to avoid buying anything for it. Sort of a junkbox project to see what could be done using the parts I have. The geiger muler tubes I have require 400 volts. I could do it easily buy buying 200 volt zener diodes and put two in series. Or I could buy a 400 volt gas discharge tube from a Soviet geiger counter cheapl...


3-terminal reg startup problems: dual supplies

Started by Bruce Varley in sci.electronics.design8 years ago 16 replies

Having problems with some audio gear. Few 5536 low noise opamps doing fairly standard audio things. The power supply is +/-8V, from a pair of HW...

Having problems with some audio gear. Few 5536 low noise opamps doing fairly standard audio things. The power supply is +/-8V, from a pair of HW rectifiers onto 470u caps, providing about +/- 13v unregulated. The +8v supply is provided by a 7808 reg, and the -8 volts by a resistor and a zener in series. When the power is applied, the 7808 sometimes fails to kick in, its output holds a...


MC34063 Step-down Converter Heating Problem

Started by Anand P. Paralkar in sci.electronics.design9 years ago 21 replies

Hi, I have constructed a DC-DC step-down converter using the MC34063. The circuit I use is very similar to the one shown...

Hi, I have constructed a DC-DC step-down converter using the MC34063. The circuit I use is very similar to the one shown here: http://www.eleccircuit.com/wp-content/uploads/2008/01/ipod-mp3-player-charger-by-mc34063.jpg My circuit does not have the Zener, output side LED and input side protection diodes (TVS1 and D2 in the circuit). The rest of the circuit is quite similar. The...


Shunt Regulator

Started by Anonymous in sci.electronics.design8 years ago 18 replies

Hi, Devices: 1. BJT Transistor : http://www.diodes.com/datasheets/ZTX650.pdf 2. DC TO DC Converter :...

Hi, Devices: 1. BJT Transistor : http://www.diodes.com/datasheets/ZTX650.pdf 2. DC TO DC Converter : http://cds.linear.com/docs/Datasheet/3970fb.pdf 3. Zener Diode : http://www.digikey.com/product-detail/en/1N5364B-TP/1N5364BTPMSCT-ND/1114306 Schematics: Figure 1 and Figure 2 http://img836.imageshack.us/img836/7381/systemblockdiagramc.jpg Problem Description: A) Figure 1 ...


Zener Diode and Bridge Rectification

Started by Anonymous in sci.electronics.design8 years ago 13 replies

Hi, The 100 KHz magnetic field is cutting the inductor L1 as shown in Figure 1 = and introducing sine voltages across it in range of 40 volts...

Hi, The 100 KHz magnetic field is cutting the inductor L1 as shown in Figure 1 = and introducing sine voltages across it in range of 40 volts peak to peak t= o 70 volts peak to peak depending upon the magnitude of the magnetic field.= I do not know how much flux is there or magnetic field.=20 Wave form specs: 1. Voltage equals to 40 to 70 volts peak to peak sine wave across L1=20 2....


Track another Voltage rail with fixed 5V drop @500mA question

Started by The Hemulen in sci.electronics.design7 years ago 38 replies

I need a Voltage rail to track another rail with a fixed 5V drop between the two. ie if main rail is at 16V output at 11V, main rail drops to...

I need a Voltage rail to track another rail with a fixed 5V drop between the two. ie if main rail is at 16V output at 11V, main rail drops to 15V output at 10V etc. Need to pull up to 500mA from this tracking output. An obvious way would be a series power NPN transistor with 5V6 zener between collector and base and resistor from here to ground but I'd also like the tracked output to ha...