Optocoupler and probing

Started by john in sci.electronics.design10 years ago 8 replies

Hello, I am trying to interface my FPGA board to the DAC board. The DAC needs four lines from the FPGA to work properly . I optocially...

Hello, I am trying to interface my FPGA board to the DAC board. The DAC needs four lines from the FPGA to work properly . I optocially isolated the four lines using four HCPL 2400. I powered up the FPGA board and DAC board separately using two different DC Lead acid battery (+5volts) inorder to preserve isolation. Now, I probed the power pins of the DAC and the optocoupler with oscillos...


DAC resolution vs. smoothing filter cutoff-freq

Started by vkj in sci.electronics.design6 years ago 8 replies
DAC

Usually the smoothing filter after the DAC is supposed to have a cut-off freq.

Usually the smoothing filter after the DAC is supposed to have a cut-off freq.


DAC and 4-20ma output

Started by sandeepa in sci.electronics.design10 years ago 4 replies
DAC

What is the resolution of the DAC generally used in temperature controllers for a 4-20ma output ? I have made a temperature controller using...

What is the resolution of the DAC generally used in temperature controllers for a 4-20ma output ? I have made a temperature controller using PIC16f877a taht gives gives either relay outputs or pulses.Now i want to give 4-20ma output as well.So i need a DAC to convert the o/p from the PIC. I was looking at AD420 which has a resolution of 16bits.However, in such apps where the proportional ban...


Calculating BW for DAC based PGA??

Started by anotherstevest in sci.electronics.design7 years ago 5 replies
DAC

Greetings, Of late I have been investigating a circuit (on paper) that includes a programmable gain stage (with an MDAC in an op-amp feedback...

Greetings, Of late I have been investigating a circuit (on paper) that includes a programmable gain stage (with an MDAC in an op-amp feedback loop in the somewhat common manner, in this case it's an LTC8043 DAC and OPA4277 op-amp). I intuitive suspect that using the DAC in the feedback loop at high gain settings is going to reduce the BW more than what the gain-bandwidth product would sug...


Problem with audio amplifier

Started by eryer in sci.electronics.design8 years ago 2 replies

Hi, I have a problem with this audio amplifier (i'm new in this field, so excuse me for my...

Hi, I have a problem with this audio amplifier (i'm new in this field, so excuse me for my questions): http://focus.ti.com/lit/ds/symlink/tpa2005d1.pdf I've used it as single ended amplifier. It is connected to a DAC: between DAC and IN- a CR high pass filter is present. DAC can generete signals from 0 to Vdd (the same Vdd of TPA2005); so a value between -Vdd/2 +Vdd/2 is present in IN-. Fro...


I2S Audio DAC : Master Clock relationship

Started by Mahen K in sci.electronics.design7 years ago 2 replies
DAC

I amd trying to interface I2S audio from MCU connected to the DAC. Is it OK if I just use the LRCLK, BCLK and SDATA from teh MCU and connect the...

I amd trying to interface I2S audio from MCU connected to the DAC. Is it OK if I just use the LRCLK, BCLK and SDATA from teh MCU and connect the clean external Master clock (128-512Fs)to the DAC ignoring the MCLK from the MCU. What does the following statement from PCM1798 datasheet mean? Is it necessary to supply th same master clock that was used by the source (MCU) to generate LRCLK and BC...


Deglitching a DAC

Started by Spehro Pefhany in sci.electronics.design5 years ago 93 replies
DAC

Any clever ideas on getting rid of glitches in a high precision DAC output? Update rate is a fixed rate, probably in the 10-100kHz range, and...

Any clever ideas on getting rid of glitches in a high precision DAC output? Update rate is a fixed rate, probably in the 10-100kHz range, and I'd like to keep the glitches (especially variation in glitches) to < < 25ppm, preferably < 5ppm. A S&H with a low charge injection switch?


"Faking" extra resolution with an 8 bit DAC

Started by Bitrex in sci.electronics.design7 years ago 31 replies
DAC

I remember seeing an article online in one of the design mags a while back about how to "fake" extra resolution in a DAC by PWMing between...

I remember seeing an article online in one of the design mags a while back about how to "fake" extra resolution in a DAC by PWMing between adjacent values; I think there were code examples as well. Does anyone that knows what I'm talking about maybe have a link to said article? Thanks.


Cheap 12 bit DAC and ADC's

Started by Martin Riddle in sci.electronics.design8 years ago 16 replies
DAC

I'm looking for a cheap 5v Rail buffered output 12bit DAC And a 12bit ADC (8 channel). Any recommendations? Cheers

I'm looking for a cheap 5v Rail buffered output 12bit DAC And a 12bit ADC (8 channel). Any recommendations? Cheers


PCIe card with FPGA and DAC

Started by John Larkin in sci.electronics.design2 years ago 8 replies

I got a call from a really nice guy who has a tiny company in the Bahamas. Our gear is too expensive for his application, but it could be...

I got a call from a really nice guy who has a tiny company in the Bahamas. Our gear is too expensive for his application, but it could be done with a PCIe PC-plugin board that has an FPGA and a fast DAC. It would need analog bandwidth in the 30 MHz range, maybe 100M samples/sec or so. He would need help to program the FPGA, since the signal set that he needs to generate is kind of weird, ...


Pease turkey DAC?

Started by Tom Del Rosso in sci.electronics.design6 years ago 10 replies
DAC

Many years ago I read a Pease column in which he told the story of a client who was trying to design a DAC for the video display of an A4 or...

Many years ago I read a Pease column in which he told the story of a client who was trying to design a DAC for the video display of an A4 or A6 aircraft. He had to do environmental testing but it wouldn't fit in the chamber, so he put it in a turkey roasting bag and did it in a regular oven. It was a neat one, but I have never been able to find that column online. Of course I remembe...


radhard multichannel DAC

Started by alb in sci.electronics.design3 years ago
DAC

Hi everyone, I'm looking for a RADHARD multichannel 12bit DAC which can sustain 15krad or thereabout. We have 9 channels to feed and I'd like...

Hi everyone, I'm looking for a RADHARD multichannel 12bit DAC which can sustain 15krad or thereabout. We have 9 channels to feed and I'd like to avoid using 9 individual ICs for obvious reasons (surface, cost, reliability, etc.). A potential candidate if we needed a single channel would have been: DAC121S101QML (12bit/15us 2mW 100krad). Any suggestions? Thanks in advance, Al ...


DC Coupled Soundcard DAC Mod

Started by Ken Morrow in sci.electronics.design2 years ago 20 replies

I want to generate a signal in my computer that has a DC offset and output them to the real world. Unfortunately, the DC offset does not...

I want to generate a signal in my computer that has a DC offset and output them to the real world. Unfortunately, the DC offset does not pass through my soundcard. So I found this "solution" online. http://www.whence.com/soundcard-dc-dac/ What the article does not state is that the large chip on the circuit board gets very hot trying to pump out DC instead of the bipolar signal it...


Digital Analog converter for resonator circuit

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

Hi I have dual resonator circuit consists of Inductors, capacitors and resistors. I am generating sine wave with amplitude of 1 from DAC...

Hi I have dual resonator circuit consists of Inductors, capacitors and resistors. I am generating sine wave with amplitude of 1 from DAC and write a frequency sweep function in Matlab however I only get a single resonator response and I am missing the second peak. when I connect 1 ohm or any value less than that in parallel with DAC I am able to get both peaks. I can also get both peak when I am...


dac dithering

Started by John Larkin in sci.electronics.design4 years ago 41 replies

OK, I'm sort of thinking this through. Suppose I have a stream of parallel digital words that represent a waveform. Assume it's audio or...

OK, I'm sort of thinking this through. Suppose I have a stream of parallel digital words that represent a waveform. Assume it's audio or something similar. Further assume that it has an arbitrary number of bits available at an arbitrarily high rate; we can fake the rate by digital interpolation if the raw data stream isn't fast enough. Assume that I want to use a 16 bit DAC but I nee...


Many switches, single line

Started by Bobby Joe in sci.electronics.design6 years ago 9 replies

Are there cheap SPST switches that have built in single wire comm. that can all be hooked up serially? Or is there an efficient method to...

Are there cheap SPST switches that have built in single wire comm. that can all be hooked up serially? Or is there an efficient method to allow for expanding the number of switches easily? I was thinking of a possible DAC like setup but this limits the number of switches and speed and may be error prone. 16 switches would require a 16-bit DAC. What I'd like is a single 1 wire interfac...


MicroController control for switching regulator

Started by RogerN in sci.electronics.design1 year ago 72 replies

I'm wanting to use a microcontroller to control the output of a switching regulator, maybe something like a LM2576 simple switcher. I see the...

I'm wanting to use a microcontroller to control the output of a switching regulator, maybe something like a LM2576 simple switcher. I see the adjustability is on the feedback lead but what's the best way make it adjustable from a microcontroller. I'm guessing the feedback may be used in switching timing, ie, I guess I can't just use a DAC and get an output of 1.23V more than the DAC ...


simulating a digital control loop

Started by John Larkin in sci.electronics.design8 years ago 41 replies

I'm designing a gadget that uses an ARM uP, with 12-bit mux'd ADC and a 10-bit DAC, to essentially make a current and voltage regulated power...

I'm designing a gadget that uses an ARM uP, with 12-bit mux'd ADC and a 10-bit DAC, to essentially make a current and voltage regulated power supply. The ADC will measure voltage and current and the DAC will control a fairly soft source-follower series-pass mosfet. The customer load could be most anything. I think it would be time-effective to simulate the control loop while the PC board i...


Computerized Audio Project.

Started by Ken S. Tucker in sci.electronics.design7 years ago 34 replies

We using the printer cable to send 8 bit waveforms to a speaker. I figure using a DAC-08 (D to A converter) will create any sound we want, in...

We using the printer cable to send 8 bit waveforms to a speaker. I figure using a DAC-08 (D to A converter) will create any sound we want, in 0-255 amplitudes. Essentially were making a speech synthesizer. Ken


THD and DC performance

Started by Vladimir Vassilevsky in sci.electronics.design8 years ago 30 replies
DAC

Is there such DAC in the world, that would allow for: * pure THD ~ 0.0001%, SNR is not very critical. * frequency response up to several...

Is there such DAC in the world, that would allow for: * pure THD ~ 0.0001%, SNR is not very critical. * frequency response up to several kHz * DC accuracy in 10mV range Vladimir Vassilevsky DSP and Mixed Signal Design Consultant http://www.abvolt.com