Hacking audio amplifier

Started by DaveC in sci.electronics.design9 years ago 3 replies

A set of Harman Kardon Soundsticks are obsolete with most modern computers. They originally took digital audio via USB output from the computer...

A set of Harman Kardon Soundsticks are obsolete with most modern computers. They originally took digital audio via USB output from the computer and fed it to a multi-channel audio amplifier chip which drove 2 desktop speakers and a sit-on-the-floor subwoofer. USB drivers are no longer available. I'd like to make these work again by connecting the audio-out jack from the computer to the...


Thermocouple Amplifier Design what are the most critical parameters in an Op Amp used?

Started by Myauk in sci.electronics.design9 years ago 4 replies

Dear All, Currently I am working on a thermocouple amplifier design with an approximate gain of 240. The reference circuit is from...

Dear All, Currently I am working on a thermocouple amplifier design with an approximate gain of 240. The reference circuit is from Microchip http://ww1.microchip.com/downloads/en/appnotes/00844a.pdf. There they recommended to use MCP619 which is a bit expensive op amp. I would like to use cheaper op amps like LM324. I know that the offset compensation scheme, CMRR etc are different if we c...


Imput impedance of common emitter amplifier at RF frequencies

Started by amal banerjee in sci.electronics.design1 year ago 36 replies

Could some electronics guru here please clarify this a bit ? What is the input impedance for a common emitter BJT amplifier operating at RF...

Could some electronics guru here please clarify this a bit ? What is the input impedance for a common emitter BJT amplifier operating at RF frequencies ? The output impedance id the parallel combination of the collector resistor Rc and the load resistor. All hints, suggestionas are welcome. Thanks in advance.


Small IC power amplifier challenge

Started by Glenn in sci.electronics.design7 years ago 1 reply

Do you know a better, cheaper smaller LM386-like IC power amplifier bugger than these?: Preferably: * Less than e.g. 10 legs * Might be...

Do you know a better, cheaper smaller LM386-like IC power amplifier bugger than these?: Preferably: * Less than e.g. 10 legs * Might be heat sinkable * Thermal protection * Short-circuit proof * Missing Current Limiter (MCL) ? No switch-on and off clicks "depops" * Low quiescent power consumption e.g. 4mA * Bridged output so big output capacitors are not needed * Wide power supply vo...


LTspice simulation is taking too long to run

Started by MUHAMMAD FAHAD BHUTTA in sci.electronics.design5 years ago 11 replies

Greetings people ! So lately, I have been working on my Sigma Delta ADC and before going advance, I wanted to have a base model WORKING (1ST...

Greetings people ! So lately, I have been working on my Sigma Delta ADC and before going advance, I wanted to have a base model WORKING (1ST ORDER, 3 bit digital output) . The circuit is quite simple. Input (x) -> Difference Amplifier -> Integrator (op-amp) -> Quantizer-> Encoder -> 3-bit Output (Y) -> Feedback DAC to the non-inverting pin of Difference Amplifier (I am using I


AD8066 buffer oscillates with inductor on input

Started by Chris Jones in sci.electronics.design3 years ago 7 replies

Hi all, Someone at work wanted a buffer to drive a coax cable with a signal from a high impedance device. I thought this would be a quick job...

Hi all, Someone at work wanted a buffer to drive a coax cable with a signal from a high impedance device. I thought this would be a quick job so I built a buffer amplifier, using half of an AD8066 configured as a unity-gain buffer. I know that op-amps don't like capacitive loads, so I connected a 50 Ohm resistor between the cable and the buffer amplifier and also terminated the other ...


How to compute base biasing resistor for class C amplifier

Started by amal banerjee in sci.electronics.design11 months ago 9 replies

Could some electronics guru here please tell me how to compute the base biasing resistor for class C amplifier. From the Vce-Ice- load line...

Could some electronics guru here please tell me how to compute the base biasing resistor for class C amplifier. From the Vce-Ice- load line graph, the Q point has to be below the horizomtal axis, i.e., Vce < 0.0. All hints, suggestions are welcome. Thanks in advance.


Sziklai pair power amplifier bias

Started by bitrex in sci.electronics.design5 years ago 24 replies

I was looking over the schematic for the Roland Jazz Chorus amplifier, and the power amp section seems pretty standard, except for the fact...

I was looking over the schematic for the Roland Jazz Chorus amplifier, and the power amp section seems pretty standard, except for the fact that the designers apparently chose to use a "PNP" configured Sziklai pair as the bias voltage source, to set the quiescent current in the output devices (biased into class AB I'd guess.) Bottom right: http://tinyurl.com/h4jnsg2 Any ideas as t...


current amplifier or current to voltage op-amp

Started by Anonymous in sci.electronics.design7 years ago 49 replies

Hi, I want to measure very weak piezoelectric signal from a quartz crystal dete= ctor that mechanically vibrate. Although I can simply...

Hi, I want to measure very weak piezoelectric signal from a quartz crystal dete= ctor that mechanically vibrate. Although I can simply measure the output using a preamp, such as SRS 560, i= t seems I will need a "trans impedance amplifier" to convert the current si= gnal to voltage signal, in order to provide a virtual ground and avoid load= ing the detector, if my understanding is right...


Compound fully differential amplfiers

Started by speff in sci.electronics.design3 years ago 13 replies

Hi, all:- The fully differential amplifiers used to drive high res 24+ bit ADCs such as the OPA1632 have excellent AC characteristics (noise &...

Hi, all:- The fully differential amplifiers used to drive high res 24+ bit ADCs such as the OPA1632 have excellent AC characteristics (noise & distortion, for example) but horrible DC drift and resulting drift and low frequency noise- worse than a 1960s 741 amplifier. Is there a straightforward way of combining a zero drift or ultra precision amplifier (or in-amp) with a fully


Re: Why Adding a Voltage Amplifier after a Transimpedance Amplifier reduce BW? Book Claim by 0.64

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

On 5/17/2015 7:27 PM, Felipe Jimenez wrote: > On Sunday, May 17, 2015 at 5:16:19 AM UTC-7, Phil Hobbs wrote: > > > Hey Phil...Just to clarify,...

On 5/17/2015 7:27 PM, Felipe Jimenez wrote: > On Sunday, May 17, 2015 at 5:16:19 AM UTC-7, Phil Hobbs wrote: > > > Hey Phil...Just to clarify, you're suggesting a 2kohm resistor to > > > gnd on all c-multiplier outputs (3 of them: +/- 10V for the > > > opamps and -10V for the PD), right? we'll try using a x10 scope > > > probe for the non-inverting configuration. > > > > So, Felipe, did that fix it?


Error Amplifier Design for SG3524

Started by Myauk in sci.electronics.design9 years ago 4 replies

Dear All, I am now making a 48 V to 120V Boost Converter (with a single series 560uH 10A inductor) using PWM IC SG3524, and I am a little...

Dear All, I am now making a 48 V to 120V Boost Converter (with a single series 560uH 10A inductor) using PWM IC SG3524, and I am a little bit confused with the use of error amplifier input pins (pin 1 and pin 2) and the compensation pin (pin 9). A typical example application circuit (see figure 13) divides the reference voltage 5V to 2.5V, and feeds it to pin 2 as reference. The output is ...


multistage differential amplifier - stability

Started by wolti in sci.electronics.design5 years ago 8 replies

Dear All, I have recently worked on a new multistage amplifier and I experience some stability issues where I would be very grateful for some...

Dear All, I have recently worked on a new multistage amplifier and I experience some stability issues where I would be very grateful for some tips. As it is only working in a closed loop debugging the individual stages is difficult due to biasing and high gain. Input-Stage: => Input is AC coupled. => DC operating point is by the 1Meg bias resistor. => Differential NPN stage with activ


IC of amplifier in EMCO probe kit?

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

Does anyone know what IC they use in the amplifier of this probe kit? The P/N of the amp is 7405-907B and goes to...

Does anyone know what IC they use in the amplifier of this probe kit? The P/N of the amp is 7405-907B and goes to 3GHz. http://www.bellnw.com/media/images/products/ETS/7405.jpg It is a simple TO-92 metal can, four pins, IN, OUT, V+ and GND. Needless to say there is no lettering on it, bare metal. Just the supply, no inductor like with MMIC. Cap in, cap out, that's it. This amp is used ...


9-decade transimpedance amplifier

Started by Winfield Hill in sci.electronics.design1 year ago 33 replies

Here's a TIA circuit published in 2012, in RSI, by Yale physicist, Stephen Eckel. ?A high dynamic range, linear response transimpedance...

Here's a TIA circuit published in 2012, in RSI, by Yale physicist, Stephen Eckel. ?A high dynamic range, linear response transimpedance amplifier.? It's easy to implement, and super useful. The TIA has multiple ranges, each with its own output, but multiple ranges are active at once; there's no loss of data as would happen switching range resistors. Stephen and his co-authors ...


25kV AC

Started by Winfield Hill in sci.electronics.design12 months ago 72 replies

We need a 25kV rms AC signal. OK, that's 70kV p-p. I had a 30kV Trek model 678 amplifier, a huge beast procured on eBay, but I fear it...

We need a 25kV rms AC signal. OK, that's 70kV p-p. I had a 30kV Trek model 678 amplifier, a huge beast procured on eBay, but I fear it was thrown away in a downsizing move, damn! With that we could make a 10kV rms AC signal, at a frequency of our choice. And maybe transform it up to 25kV. Years ago I made RIS-333 / RIS-470, a 10kV 600kHz amplifier / resonant-transformer for ...


input/output crosstalk/noise in AC inverting amp

Started by Anonymous in sci.electronics.design1 year ago 5 replies

we have an inverting opamp as AC amplifier with gain 100 or 1000 in a shielded aluminum box. BNC as input and output. Using chopped light and...

we have an inverting opamp as AC amplifier with gain 100 or 1000 in a shielded aluminum box. BNC as input and output. Using chopped light and measuring noise on top of a signal with a lockin amplifier. I am wondering why different ops behave differently. We had it on the table so that input and output BNC crossed each other at ca. 90°. Not optimal, I know, so we rotated the al


I need a good text on low noise amplifier design ASAP

Started by Anonymous in sci.electronics.design4 years ago 59 replies

I'm struggling with an amplifier design for a radio front end. Ham 600 meter band (475kHz) The antenna is a ferrite loop (can't change...

I'm struggling with an amplifier design for a radio front end. Ham 600 meter band (475kHz) The antenna is a ferrite loop (can't change that) with a resonating capacitor on the primary, and a few turns on the secondary, so I have a pretty low input impedance. I have several designs in spice, with common emitter and common base configurations, but I am struggling to get the noise below 300...


Amplifier with very low input- design search

Started by captoro in sci.electronics.design6 years ago 18 replies

Hello guys, I am building an extremely low input (voltage) amplifier, with about .2 volt spikes and also -0.2 volt spikes. I just need to...

Hello guys, I am building an extremely low input (voltage) amplifier, with about .2 volt spikes and also -0.2 volt spikes. I just need to detect if there is a voltage, either positive or negative then turn on a led when it is detected. My questions are as followes, - do I need negative supply ( in the case i use an opamp, i guess I will need +/- supply) - Why can I use at the input to inver...


DDS Selection

Started by spflanze in sci.electronics.design9 years ago 111 replies

I am designing designing a system that uses changes in the transmissivity light in a detection chemistry to detect gas. The light source is a...

I am designing designing a system that uses changes in the transmissivity light in a detection chemistry to detect gas. The light source is a sine wave modulated LED source. After the light passes through the detection chemistry it will be measured by a photodiode and a transimpedance amplifier circuit. The output of the transimpedance amplifier is measured by a 16 bit AD7606 ADC which does ...