Isolated high voltage opamp

Started by bitrex in sci.electronics.design7 years ago 21 replies

So I have a need for an analog isolation amplifier thing into a HV section at low audio frequencies. I remembered the "HV opamp" thing that...

So I have a need for an analog isolation amplifier thing into a HV section at low audio frequencies. I remembered the "HV opamp" thing that John Larkin posted a while back and that seems to work well, but I'd like to isolate the feedback via pwming it and sending it back across the barrier via an optocoupler and integrating. I dont really want to chop it first and have more LV elec...


How to design a 12V 2A power supply

Started by Anonymous in sci.electronics.design5 years ago 26 replies

I bought a stereo amplifier on ebay for $7. It's a complete amp except for a housing. I'll make my own housing. It's made to be used in a...

I bought a stereo amplifier on ebay for $7. It's a complete amp except for a housing. I'll make my own housing. It's made to be used in a car. It has output of 15W per channel. Instead of buying those cheap computer speakers which seem to never last more than a year, and dont have very good sound anyhow, I want to connect this amp to some quality bookshelf speakers that I already have. ...


RF power question

Started by John Larkin in sci.electronics.design3 years ago 78 replies

We have an acquaintance who wants to put a roughly 1 KV (2K p-p) sine wave into a roughly 12 pF load near 500 MHz. He wanted us to...

We have an acquaintance who wants to put a roughly 1 KV (2K p-p) sine wave into a roughly 12 pF load near 500 MHz. He wanted us to modify our Pockels Cell driver, but that makes kilovolt or so unipolar gaussian pulses at 0-5 MHz. Seems like what he wants is an RF power amplifier and some sort of high-Q matching network. We are not RF people. Any suggestions for him? What to buy, how ...


What Is This Strange Valve Circuit?

Started by Robert Miller in sci.electronics.design5 years ago 6 replies

The valve circuit below appears to be a type of four stage amplifier. https://app.box.com/s/miv1o6y2ejt0zj4xz04qp9uedk8ihq6w Can anyone tell...

The valve circuit below appears to be a type of four stage amplifier. https://app.box.com/s/miv1o6y2ejt0zj4xz04qp9uedk8ihq6w Can anyone tell me the approximate gain and bandwidth? The 60" antenna would tend to indicate 197MHz full wave, but is this (or quarter wave) a valid assumption considering the components used? Does the circuit do anything other than amplify, e.g. oscillate due ...


Unusual Bias Method

Started by Jim Thompson in sci.electronics.design9 years ago 198 replies

Here's half of the full H-bridge amplifiers that I built for my 1977 280Z... Image scanned in quarters and pieced together for...

Here's half of the full H-bridge amplifiers that I built for my 1977 280Z... Image scanned in quarters and pieced together for easier understanding... No one has commented on the unusual bias scheme in this amplifier since I originally posted it. No actual circuit designers in our midst ?:-}


Toob Amplified PC Speakers

Started by Tim Wescott in sci.electronics.design8 years ago 56 replies

It's winter, and the amplifier in my PC speakers just died. I think it'd be kinda cool to have a toob speaker amp, but I'm too lazy (and...

It's winter, and the amplifier in my PC speakers just died. I think it'd be kinda cool to have a toob speaker amp, but I'm too lazy (and time-challenged) to build one up from scratch. Are there, by any chance, kits out there? I'm not looking for nickel- cored transformers with solid silver windings, genuine paper caps rolled on the thighs of virgins, toobs dipped in LN2, and all that c...


Amplifier startup problem

Started by Sylvia Else in sci.electronics.design6 years ago 50 replies

I've implemented the circuit on page 2 of http://www.ti.com/lit/ds/symlink/lm1875.pdf with the addition of 1K resistors across the 100uF...

I've implemented the circuit on page 2 of http://www.ti.com/lit/ds/symlink/lm1875.pdf with the addition of 1K resistors across the 100uF capacitors to define ground as being midway between the power rails. Most of the time, it works fine, but occasionally when it starts, it pulls the ground down to 1.8 volts or so above the negative power rail, and holds it there. I have multiple in...


Floating digital pot query.

Started by Clive Arthur in sci.electronics.design4 years ago 12 replies

I have a small-signal amplifier with adjustable gain and HF lift which uses digital pots. It's differential, actually a few identical stages....

I have a small-signal amplifier with adjustable gain and HF lift which uses digital pots. It's differential, actually a few identical stages. At high lifts, there's more noise than I'd like. To cut a long story short, I can very much improve it by reconfiguring the lift digipot (actually used as a variable resistor) and associated components, but the upshot is that the digipot element ...


How is RF BJT bias current value calculated

Started by Anonymous in sci.electronics.design5 years ago 15 replies

Could some electronics guru please shed some light on this ? For a non-RF BJT amplifier a simple design rule is to set the maximum base or...

Could some electronics guru please shed some light on this ? For a non-RF BJT amplifier a simple design rule is to set the maximum base or biasing current to 1/10 of the calculated collector current. Does tha same rule apply to RF BJTs as well ? Thanks in advance.


Blowhard Larkin - DEFINE the Problem

Started by Jim Thompson in sci.electronics.design9 years ago 85 replies

Hey! Blowhard Larkin! How about you stating here _exactly_ what you _think_ the failure mechanism of my amplifier is... DEFINE the...

Hey! Blowhard Larkin! How about you stating here _exactly_ what you _think_ the failure mechanism of my amplifier is... DEFINE the Problem! Then I will systematically PROVE you wrong. Inquiring minds want to see you put down once and for all. No bloviating, sneering, name-calling, "sliming", or whatever. Just state the electronics issue. If you don't, everyone will know exactly ...


Need help finding specs

Started by Anonymous in sci.electronics.design5 years ago 2 replies

I have some isolation amplifiers from Aikoh but can't find a data sheet. Cover says MAZ-02 ulta low noise high gain isolation amplifier (see...

I have some isolation amplifiers from Aikoh but can't find a data sheet. Cover says MAZ-02 ulta low noise high gain isolation amplifier (see pic). Any thoughts on where to find data sheet? http://www19.zippyshare.com/v/ely4qRdu/file.html Scot


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


op-amp signal delay

Started by Winfield Hill in sci.electronics.design7 years ago 45 replies

I'm playing with a TI op-amp, the THS4304. It's marked as a 3GHz op-amp on the datasheet's title page, but it has a 935 MHz GBW at G=5. ...

I'm playing with a TI op-amp, the THS4304. It's marked as a 3GHz op-amp on the datasheet's title page, but it has a 935 MHz GBW at G=5. Whatever, it is one of the faster VFB opamps you can get. Its evaluation board comes loaded with parts for a non-inverting G=2 amplifier (two 249-ohm resistors). Both my scope and my pulse generator advertise a 0.8ns risetime. Setting up a short 250mV p...


2 GHz buffer with 2N390x

Started by Anonymous in sci.electronics.design2 years ago 22 replies

...

https://www.allaboutcircuits.com/technical-articles/voltage-buffer-simulation-composite-amplifie r-simulation-boost-output-current-drive/ -- John Larkin Highland Technology, Inc The cork popped merrily, and Lord Peter rose to his feet. "Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"


Symmetrical DC Offset - See Dual Op Amp Ckt.

Started by Anonymous in sci.electronics.design9 years ago 33 replies

The amplifier circuit linked below produces two identical outputs, one each above and below the DC line....

The amplifier circuit linked below produces two identical outputs, one each above and below the DC line. http://www.4shared.com/photo/5tn1xsXO/dual_polarity_amp.html Hover over the right bottom corner and click the icon to enlarge. What I would like to do is create a greater symmetrical DC offset between the two. Something like 3 volts. IOW the low side of channel A would rest at 1....


Running out of ideas: stability, bootstrap

Started by Gerhard Hoffmann in sci.electronics.design5 years ago 24 replies

Hi, all, we had a bank holiday here, nicely positioned close to the weekend and I took the free time to play with my multi-IF3601 low noise...

Hi, all, we had a bank holiday here, nicely positioned close to the weekend and I took the free time to play with my multi-IF3601 low noise amplifier. That was not so funny because it features a negative input impedance over most frequencies, so with a suitable inductance on the input it makes a stable oscillator. Some observations: - Zin is negative also with the feedback loop cu...


Spot the Design Error 2

Started by Phil Allison in sci.electronics.design3 years ago 34 replies

Hi to my many admirers, see schem for tube instrument amplifier, the famous Fender "Bassman 50"....

Hi to my many admirers, see schem for tube instrument amplifier, the famous Fender "Bassman 50". https://schematicheaven.net/fenderamps/fender_bassman50.pdf Thousands made and sold, yet it has a fatal design flaw. Owners can, in a single step that they would never imagine was hazardous, instantly damage or destroy output tubes and/or the output transformer. This during ...


OT: Should this receiver get hot?

Started by John Doe in sci.electronics.design2 years ago 25 replies

Generally speaking, a receiver (with no output amplifier) requires extremely little power? That's because they are listening for tiny signals,...

Generally speaking, a receiver (with no output amplifier) requires extremely little power? That's because they are listening for tiny signals, therefore only tiny current is required? So why is my device getting hot? I realize it might be using the case as a heatsink, I'll open it up sooner or later. But what causes the heat, the video signal output circuit? Thanks. 40 Channel 5.8GH...


interim layout

Started by Anonymous in sci.electronics.design1 year ago

I like to do the tricky parts of a pcb layout myself, rather than trying to explain it to a pcb designer. Actually, I don't know how parts...

I like to do the tricky parts of a pcb layout myself, rather than trying to explain it to a pcb designer. Actually, I don't know how parts should be arranged until I push things around for a while. It's chaos until something clicks. https://www.dropbox.com/s/rgjkb17itlkpud3/Z508A3_pcb1.jpg?raw=1 That has two 20 GHz $20 MMICS summing into a 20 GHz $350 distributed amplifier. That's sc...


Critic of circuit before I build it.

Started by amdx in sci.electronics.design7 years ago 21 replies

I'm about to build this circuit to compare output from different ferrite receive antennas. I will be using it with the the FET...

I'm about to build this circuit to compare output from different ferrite receive antennas. I will be using it with the the FET amplifier referenced at the bottom of the page, so the input impedance is not a concern. I'm mostly interested in the DC output to monitor signal levels. AM band frequencies. http://www.crystal-radio.eu/diodedetector/endiodedetector.htm Any fix for the si...