Is this just diode noise?

Started by amdx in sci.electronics.design5 years ago 3 replies

Hi all, I'm working on a circuit to test LC ferrite antennas. I found the amp output very noisy with the rectifying diode in the circuit. I can...

Hi all, I'm working on a circuit to test LC ferrite antennas. I found the amp output very noisy with the rectifying diode in the circuit. I can hear the noise and measure it on my meter. Very little noise without the diode. See the link below for a block drawing of the circuit with and without the diode. > http://theradioboard.com/rb/download/file.php?id=4374 Is it simply the diode noi


reverse biased diode variable resistance experiment

Started by Jamie M in sci.electronics.design7 years ago 15 replies

Hi, This is related to the "poor mans superconductor wire" thread, for testing an idea of anomalous resistance decrease in a diode. If you...

Hi, This is related to the "poor mans superconductor wire" thread, for testing an idea of anomalous resistance decrease in a diode. If you reverse bias a diode, then electrons move closer to the junction of the diode as the voltage pressure increases. I was thinking maybe this biasing of the electric field will change the electrical resistance on each side of the diode. Ie. if the actu...


A diode in series with a brushed universal motor?

Started by John Doe in sci.electronics.design6 years ago 5 replies

Not concerned about safety for this discussion. What will happen if you put a diode in series with a universal brushed motor? Of course...

Not concerned about safety for this discussion. What will happen if you put a diode in series with a universal brushed motor? Of course talking about a diode that can handle standard USA 120 V 60 Hz household power. Just putting a diode on one of the wires coming from the outlet, to rectify the current. Would a capacitor after the diode be useful? What sort of capacitor would be require...


Simple Circuit question

Started by Ivan Vegvary in sci.electronics.design4 years ago 15 replies

Doing self study. Diode circuit. 10V battery followed by series load resistor. Thence a resistor and diode in parallel and back to the...

Doing self study. Diode circuit. 10V battery followed by series load resistor. Thence a resistor and diode in parallel and back to the battery. Simple to take the 0.7v drop of the diode and have 9.3V remaining on across the first resistor. This allows calculation of total current through circuit and the rest is easy. BUT Then they want you to use the "ideal diode" method to solve same problem....


How long does it take for a diode to conduct?

Started by Tim Wescott in sci.electronics.design8 years ago 79 replies

Is it reasonable to expect that the turn-on (not off -- _on_) time of a diode should be pretty much consistent with the inductance of the...

Is it reasonable to expect that the turn-on (not off -- _on_) time of a diode should be pretty much consistent with the inductance of the package, and not much else? A customer just sent me some O-scope traces of a circuit where a voltage at a catch diode anode is (at least apparently) going several hundred volts above its cathode for a microsecond before settling out to the nominal a...


diode recovered charge

Started by John Larkin in sci.electronics.design6 years ago 57 replies

I got curious about the amount of reverse-recovery charge in PN diodes, as a function of forward current (and time of fwd bias) and diode...

I got curious about the amount of reverse-recovery charge in PN diodes, as a function of forward current (and time of fwd bias) and diode size/type. Question is, are the LT Spice diode models realistic? We'll have to test some diodes to see. Since diode recovery for a given part number depends a lot on the manufacturer, we should stick to sole-source parts and tweak the Spice model to al...


Gilbert cell question

Started by Anonymous in sci.electronics.design2 years ago 11 replies

Apparently, when used in the continuous mode, (as opposed to the switched mode) the local oscillator input to a needs to be distorted with a...

Apparently, when used in the continuous mode, (as opposed to the switched mode) the local oscillator input to a needs to be distorted with a diode circuit. What is exactly this diode circuit -- a single diode or something more complex. Thanks in advance.


reverse voltage protection with parallel diode

Started by Anonymous in sci.electronics.design8 years ago 11 replies

I have a diode 1N5402 connected in parallel reverse biased across the power= supply for reverse polarity protection. The maximum absolute...

I have a diode 1N5402 connected in parallel reverse biased across the power= supply for reverse polarity protection. The maximum absolute ratings of t= he load IC says -0.3V to +30V. If reverse power is applied, anything above = diode's forward drop it will short circuit and break the fuse. No issue her= e. If, let's say, 0.5V is applied in reverse, the diode will not conduct an= d reverse ...


TEC for laser diode

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

I have a laser diode that is cooled by a fan and a heat sink. I have a small TEC lying around and I would like to integrate that to the laser...

I have a laser diode that is cooled by a fan and a heat sink. I have a small TEC lying around and I would like to integrate that to the laser diode head. How do I go about controlling the voltage supply to maintain a stable temperature. Thanks for you valuable input


Double balanced diode mixer question

Started by Anonymous in sci.electronics.design2 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.design1 year 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


PING: Kevin Aylward, Diode Model Question

Started by Jim Thompson in sci.electronics.design6 years ago 8 replies

Hi Kevin, Suppose I wanted to model JUST the capacitance portion of a diode? No DC current, etc. The equation "fold-over" at VD~FC*VJ...

Hi Kevin, Suppose I wanted to model JUST the capacitance portion of a diode? No DC current, etc. The equation "fold-over" at VD~FC*VJ looks to be PITA to implement. Maybe you know of a way to trick a full diode model into not doing its DC thing ?:-} ...Jim Thompson -- | James E.Thompson | mens | | A...


"reverse diode"

Started by jon....@gmail.com in sci.electronics.design8 years ago 38 replies

Is there a passive device similar to a diode that has low impedance at 0 fo= rward voltage and high impedance at some larger voltage? e.g.,...

Is there a passive device similar to a diode that has low impedance at 0 fo= rward voltage and high impedance at some larger voltage? e.g., flip the diode curve horizontally then center the knee of the several= hundred mV above 0V. One can emulate such a device a number of ways more or less but can one be = made based on fundamental physical principles so that it behaves very simil= ar ...


Hot-carrier diode substitute

Started by garyr in sci.electronics.design7 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...


Rectifier Schottkies in parallel

Started by Piotr Wyderski in sci.electronics.design6 years ago 22 replies

Hello, many Schottky rectifier diodes contain two diodes within a single package, usually with the cathodes connected. Does it make sense to...

Hello, many Schottky rectifier diodes contain two diodes within a single package, usually with the cathodes connected. Does it make sense to connect the anodes too in order to get a diode which can withstand higher current? Is a 2x30A diode more or less equivalent to a single 60A diode? I am thinking of VBT6045CBP if it helps. The application: a high-current 50Hz rectifier. Best r...


Sampler diodes with more barrier height?

Started by Joerg in sci.electronics.design6 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.design7 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...


LT Spice diode c-v

Started by John Larkin in sci.electronics.design3 years ago 5 replies

A diode model looks like .model 1N4148 D(Is=2.52n Rs=.568 N=1.752 Cjo=4p M=.4 tt=20n Iave=200m Vpk=75 mfg=OnSemi type=silicon) If I...

A diode model looks like .model 1N4148 D(Is=2.52n Rs=.568 N=1.752 Cjo=4p M=.4 tt=20n Iave=200m Vpk=75 mfg=OnSemi type=silicon) If I want to model some other diode c-v curve, I can edit Cjo as needed. But what parameter would change the shape of the curve, how c declines with voltage? I'm modeling a weird photodiode and I can get close to the actual datasheet values, but the shape ...


JFET used as a diode

Started by Piotr Wyderski in sci.electronics.design2 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...


Little thermal thing

Started by George Herold in sci.electronics.design2 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) ...