Some capacitor leakage measurements

Started by Tim Williams in sci.electronics.design2 years ago 34 replies

https://www.eevblog.com/forum/metrology/film-and-ceramic-capacitor-leakage-current/ Tim -- Seven Transistor Labs, LLC Electrical...

https://www.eevblog.com/forum/metrology/film-and-ceramic-capacitor-leakage-current/ Tim -- Seven Transistor Labs, LLC Electrical Engineering Consultation and Design Website: https://www.seventransistorlabs.com/


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...


C-multiplier again

Started by John Larkin in sci.electronics.design13 years ago 137 replies

I need a super-low noise power supply. I have a 15 volt switching wall-wart input and want as close to 15 volts, regulated, as I can get;...

I need a super-low noise power supply. I have a 15 volt switching wall-wart input and want as close to 15 volts, regulated, as I can get; 14 would be nice, 13.5 is OK. The LDOs that I can find are all pretty noisy and have mediocre PSRR. So I thought about using a Phil Hobbs-ian c-multiplier transistor, an R-C lowpass and an emitter follower, with a slow opamp loop wrapped around i...


SPICE gets it wrong

Started by Tim Williams in sci.electronics.design6 years ago 74 replies

Speaking of SPICE, here's a nice little circuit: https://www.seventransistorlabs.com/Images/BakerDarlington.png I discovered the oscillator on...

Speaking of SPICE, here's a nice little circuit: https://www.seventransistorlabs.com/Images/BakerDarlington.png I discovered the oscillator on the left, when attempting to build a Darlington transistor pair with a Baker clamp. (In practice, R10 comes from a logic voltage input, and R2 is a load, often inductive. R14 is optional, but exacerbates the oscillation, making it reproducible.)...


Domestic US source for small quantity of CA3127 transistor array?

Started by Steve Goldstein in sci.electronics.design6 years ago 18 replies

I'm looking for one or two of these arrays for a small home project. Yes, I know they're available from China on eBay, but I'd much rather find...

I'm looking for one or two of these arrays for a small home project. Yes, I know they're available from China on eBay, but I'd much rather find a couple of vintage (and authentic and working) parts from someone's bin. There may be other parts that are suitable, but this is the only array I remember where all the devices are fully pinned-out. This requirement is important and excludes LM30...


Low-leakage PNP or PMOS

Started by Piotr Wyderski in sci.electronics.design10 months ago 11 replies

Hi, knowing that you often take parts way beyond their specs, I would like to use your wisdom. I need a high-side controllable switch...

Hi, knowing that you often take parts way beyond their specs, I would like to use your wisdom. I need a high-side controllable switch capable of charging 5pF to 400V and maintaining most of that charge for a good fraction of a second. Not important if it is a PMOS or a PNP transistor. Could you please recommend me a part known for a particularly low leakage current? Or should I use...


Single transistor mixer

Started by ChesterW in sci.electronics.design7 years ago 61 replies

I need to make a mixer (a multiplier, not an adder) for sinusoid signals somewhere between about 10 kHz and 1 Mhz. This is for a lock-in-amp. My...

I need to make a mixer (a multiplier, not an adder) for sinusoid signals somewhere between about 10 kHz and 1 Mhz. This is for a lock-in-amp. My main constraint is low cost. I'd use a microcontroller with an A to D and a hardware multiplier, but I'd like to keep the cost down by using a cheaper micro. I could use a simple power-of-2 window in the micro and then only need additions to dem...


RF transistor Acrian TT5021

Started by Jeroen Belleman in sci.electronics.design7 years ago 2 replies

I got my hands on a small lot of Acrian TT5021 RF power transistors. They are bipolar RF transistors in 7mm diameter white ceramic pucks...

I got my hands on a small lot of Acrian TT5021 RF power transistors. They are bipolar RF transistors in 7mm diameter white ceramic pucks (probably BeO) with four wings and a stud. They are probably roughly 30W VHF amplifier transistors. Does anyone have a datasheet for these things? Google came up dry. Thanks, Jeroen Belleman


Generating this negative pulse?

Started by Terry Pinnell in sci.electronics.design4 years ago 17 replies

I have a couple of simple 555 monostables, the first to delay the triggering of the...

I have a couple of simple 555 monostables, the first to delay the triggering of the second. https://www.dropbox.com/s/6uboy3fgd0ixhxa/GenerateNegPulse-1.jpg?raw=1 But I'm struggling to extract the brief -ve pulse required for the Main mono. I thought it would prove simple. But bread-boarding various combinations of R, C, diode and NPN or PNP transistor has so far not yielded a winning comb...


bit about transistor cost

Started by Anonymous in sci.electronics.design12 months ago 63 replies

https://www.fabricatedknowledge.com/p/the-rising-tide-of-semiconductor I've also heard that the cost of one next-gen euv scanner is well...

https://www.fabricatedknowledge.com/p/the-rising-tide-of-semiconductor I've also heard that the cost of one next-gen euv scanner is well over $200M, and that the design and mask set for a high-end chip costs a billion dollars. We just don't need few-nm chips. -- Father Brown's figure remained quite dark and still; but in that instant he had lost his head. His head was always ...


LDO regulators whose outputs can be ORed together

Started by Peter in sci.electronics.design1 year ago 16 replies

Sometimes one needs to power a circuit from one source or another. Most LDOs, or indeed most normal regs, feed current back up to the source....

Sometimes one needs to power a circuit from one source or another. Most LDOs, or indeed most normal regs, feed current back up to the source. LDOs tend to use a PMOS pass transistor which has a parasitic diode. I am doing a design where I am using the Ricoh R1191 for this https://eu.mouser.com/ProductDetail/Ricoh-Electronic-Devices-Company/R1191N033B-TR-FE?qs=%2Fha2p yFaduhEV6ZG3xOqbaXpS


Hartley Oscillator: Two Coils, No Cap

Started by Kevin Foster in sci.electronics.design6 years ago 17 replies

Would it be possible to build a single transistor Hartley oscillator by substituting a pancake (spiral) coil for each leg of the center-tapped...

Would it be possible to build a single transistor Hartley oscillator by substituting a pancake (spiral) coil for each leg of the center-tapped inductor, and then placing one coil flat on top of the other so the insulation between them takes the place of the cap? If the current in each coil is made to flow opposite to the other, could their proximity to each other also be used to vary th...


Some oscilloscope pictures

Started by Sylvia Else in sci.electronics.design1 year ago 25 replies

Shows how the power transformer is directly wired to two separate boards. Not sure how, or why, they'd want to do that. Shows the...

Shows how the power transformer is directly wired to two separate boards. Not sure how, or why, they'd want to do that. Shows the hole through which the transistor has to be soldered. Note the two resistors in plastic tubing that have one end so


Better buy a new multimeter then a new battery!

Started by Jan Panteltje in sci.electronics.design14 years ago 49 replies

I was at the hardware store, needed some screws, other stuff. Found a 5 Euro digital multimeter with transistor hfe test for 5 Euro. .5%...

I was at the hardware store, needed some screws, other stuff. Found a 5 Euro digital multimeter with transistor hfe test for 5 Euro. .5% accuracy on DC it says. Did not need it, but could not resist. Took it home, did not expect it to have a battery in it, for that price. But it did, and it was new and full.... Looked up the price of a new 9 V battery on conrad.nl: 4 Euro 9 cents http://ww...


Help with high input impedance amp.

Started by Lamont Cranston in sci.electronics.design3 weeks ago 85 replies

Years ago on this group, someone worked this circuit out for me and I have finally built it. It has two problems. The input impedance is about...

Years ago on this group, someone worked this circuit out for me and I have finally built it. It has two problems. The input impedance is about 30kΩ not 500MΩ, and it rolls of way to early. I may have created the problems, I don't have the FET and transistor recommended, 2N4416 and MMBTH10. I used a BF256C and a MPSH10 through hole parts. Although I doubt that created the


Request clarification on BJT HFA3134

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

Could some electronics guru here please clarify this ? The datasheet for the NPN BJT HFA3134(from Renessas Semi.) states: The HFA3134 and...

Could some electronics guru here please clarify this ? The datasheet for the NPN BJT HFA3134(from Renessas Semi.) states: The HFA3134 and HFA3135 are Ultra High Frequency Transistor pairs that are fabricated with Intersil Corporation’s complementary bipolar UHF-1X process. The NPN transistors exhibit an fT of 8.5GHz, while the PNP transistors have an fT of 7GHz. Both types e


Cheap

Started by Klaus Kragelund in sci.electronics.design3 years ago 14 replies

Hi The LCSC website has the Hottech transistor, equivalent more or less to a...

Hi The LCSC website has the Hottech transistor, equivalent more or less to a BC847: https://lcsc.com/product-detail/Transistors-NPN-PNP_2SC1623-L6-200-400_C181167.html https://datasheet.lcsc.com/szlcsc/1810121631_Guangdong-Hottech-2SC1623-L6_C181167.pdf Interestingly, the price at 50k is a lot cheaper than we buy the BC847 at over 25 million pcs per year Anyone here use that one for...


Schottky diodes, reverse current and solar changers

Started by sonn...@gmail.com in sci.electronics.design2 months ago 13 replies

Hi all I am playing around with a solar lamp, pretty simple like this https://www.pinterest.com/pin/540150549038731182/ However I do not...

Hi all I am playing around with a solar lamp, pretty simple like this https://www.pinterest.com/pin/540150549038731182/ However I do not (yet) have D2. D1 in my case is a Schottky 1N5818, and my battery 7.2V I am surprised how much reverse current I can get through the diode. Without the solar cell, it does not turn on. There is enough current through D1 to the transistor to turn the wh...


MOSFET WTF

Started by Tim Williams in sci.electronics.design5 years ago 21 replies

VDMOS nonlinear capacitance is modeled in terms of Vgd. Too bad a real MOSFET doesn't show a steplike change in Ciss as Vgd changes sign. ...

VDMOS nonlinear capacitance is modeled in terms of Vgd. Too bad a real MOSFET doesn't show a steplike change in Ciss as Vgd changes sign. (This is easily demonstrated with the gate charge test circuit, watching the waveform at low Vdd. The cutoff slope depends only on Vds, not Vgd.) So many decades of bullshit to sift through... Tim -- Seven Transistor Labs, LLC Electrical E...


Audio amp Mystery

Started by billbowden in sci.electronics.design6 years ago 10 replies

I have a little transistor radio that was drawing excessive power from the battery. It was about 125mA at 6 volts which is 10 times too much. I...

I have a little transistor radio that was drawing excessive power from the battery. It was about 125mA at 6 volts which is 10 times too much. I found I could bend the circuit board to eliminate the problem. So, I studied the thing for an hour or so and found the problem had something to do with the audio output transformer. This radio uses an input and output transformer in a push pull a...