Delta Sigma DAC article

Started by Charlie E. in sci.electronics.design8 years ago 9 replies

Hi All, Ok, going crazy (short trip, I know...) A few months ago, I saw an article that included information on delta sigma DACs, inlcuding...

Hi All, Ok, going crazy (short trip, I know...) A few months ago, I saw an article that included information on delta sigma DACs, inlcuding some code the author had written, I belive for an 8051, to implement one in software. So, now that I finally want to try it out, I can't find it anywhere. Anyone know what magazine or have a link to that article? I thought it was in EDN, but can't f...


Multiplexer sample and hold

Started by bitrex in sci.electronics.design4 years ago 37 replies

In some old schematics for analog music synthesizers, where the analog signal path is under microprocessor control, I see that they use a...

In some old schematics for analog music synthesizers, where the analog signal path is under microprocessor control, I see that they use a multiplexer arrangement to route control voltages around being driven from a single DAC, usually like a DAC08 or something. They feed it into something like a 4051 multiplexer, followed up with a JFET input amp like a TL084 configured as a buffer, ...


continuous-play DAC

Started by John Larkin in sci.electronics.design8 years ago 8 replies

Hi, We have a customer who has a mess of digitized data from some sort of aircraft system, and wants to play it back into some box for...

Hi, We have a customer who has a mess of digitized data from some sort of aircraft system, and wants to play it back into some box for testing. It will be 2 channels of 16-bit data originally sampled at about 500 KHz, several hours worth. They want us to design a VME module with dacs and a huge amount of DRAM to store the data. We don't really want to do it - they only need a couple o...


High res PWMs

Started by Phil Hobbs in sci.electronics.design7 years ago 33 replies
DAC

Hi, all, I've been working on an automatically-tweaked noise canceller design with my trusty code and layout Sherpas-in-training (my son and...

Hi, all, I've been working on an automatically-tweaked noise canceller design with my trusty code and layout Sherpas-in-training (my son and my younger daughter). I need about 10 slow but high resolution DAC outputs for the tweaks, and I was thinking about using PWMs run from the LPC1769 processor. I can close the loop on them with an on-board delta-sigma ADC (the AD7708 or maybe ...


High resolution PWM for fake DACs

Started by Phil Hobbs in sci.electronics.design7 years ago 4 replies

Hi, all, I've been working on an automatically-tweaked noise canceller design with my trusty code and layout Sherpas-in-training (my son and...

Hi, all, I've been working on an automatically-tweaked noise canceller design with my trusty code and layout Sherpas-in-training (my son and my younger daughter). I need about 10 slow but high resolution DAC outputs for the tweaks, and I was thinking about using PWMs run from the LPC1769 processor for at least some of them. I can close the loop on them with an on-board delta-sigma...


Using Analog to Digital Converter for modulation

Started by chess in sci.electronics.design5 years ago 5 replies

Hi I have written Matlab script for BPSK modulation. The way my code works is as follow: series of 0 and 1----> NRZ data (continuous...

Hi I have written Matlab script for BPSK modulation. The way my code works is as follow: series of 0 and 1----> NRZ data (continuous rectangular pulses with amplitude -1 and 1)---> multiply by carrier----> add noise--> multiply by carrier---> integration---> detection---> Bit Error collection? I would like to know can anyone tell me where I should apply DAC and ADC ? I am wondering should it


The Anything Transmitter - progress report.....

Started by Jan Panteltje in sci.electronics.design7 years ago 2 replies

Minority report? http://www.panteltje.com/pub/anything_transmitter_fifo_test_wiring_side_IMG_3837.GIF Things work out great. As mentioned in...

Minority report? http://www.panteltje.com/pub/anything_transmitter_fifo_test_wiring_side_IMG_3837.GIF Things work out great. As mentioned in previous postings, the idea is to send IQ data (for example recorded with RTL_SDR) from a Raspberry Pi SDcard to a dual DAC AD9761 into a AD8346 quadrature modulator. 8kB FIFO Raspberry Pi -> CY7C433-25PC_FIFO -> AD9761_DAC -> AD


Opinion on Semi predictive feedback control

Started by Klaus Kragelund in sci.electronics.design3 years ago 11 replies

Hi I got a power supply working in hysteresis mode with a not very precise reference So I am wrapping a digital loop with a microcontroller...

Hi I got a power supply working in hysteresis mode with a not very precise reference So I am wrapping a digital loop with a microcontroller around it using a DAC output to tune the reference and thus the output to a precise value Right now I have it working with a very simple P regulator, so if the value measured by the ADC is off target, I just move the DAC control one LSB


quantizer for LT Spice

Started by John Larkin in sci.electronics.design5 years ago 19 replies

Here's a quantizer in LT Spice: ftp://jjlarkin.lmi.net/Quantizer.jpg It wasn't hard, but the HELP is really obscure about syntax, and...

Here's a quantizer in LT Spice: ftp://jjlarkin.lmi.net/Quantizer.jpg It wasn't hard, but the HELP is really obscure about syntax, and there is no example of a schematic with a b-source that I could find. There is a sample-and-hold schematic symbol, so one can simulate the effects of a clocked ADC or a DAC on a control loop. John Version 4 SHEET 1 880 680 WIRE 48 48 0 48 W...


goofy PWM

Started by John Larkin in sci.electronics.design5 years ago 45 replies

I need an isolated analog output (many of them, actually) with, say, 1 PPM programmability and linearity. An optocoupled DAC would be...

I need an isolated analog output (many of them, actually) with, say, 1 PPM programmability and linearity. An optocoupled DAC would be silly, so I'll use PWM. https://dl.dropboxusercontent.com/u/53724080/Circuits/PWM_WB_P470.JPG If I start at 200 MHz, and do a 20 bit (1 PPM) pwm, the output frequency would be 200 Hz. If I use a 3-pole lowpass filter (not too much delay) it has to be -...


isolated SPI Module

Started by Mark in sci.electronics.design4 years ago
DAC

Hello, I would like to introduce the recently finished isolated SPI module, which is available on Tindie, Ebay and Amazon at the...

Hello, I would like to introduce the recently finished isolated SPI module, which is available on Tindie, Ebay and Amazon at the moment. Details can be found here: http://www.maleetronic.com/boardsprojects/mlt-iso-spi-module/ Ideal in noisy enviroments where you need to communicate via SPI with Sensors, ADC's DAC's and so on... Let me know what you think about it, it's my first OSHW...


DDS wisdom

Started by Phil Hobbs in sci.electronics.design6 years ago 152 replies

Hi, all, I have a gig coming in that will have me revisiting my thesis research from nearly 30 years ago, on interferometric laser...

Hi, all, I have a gig coming in that will have me revisiting my thesis research from nearly 30 years ago, on interferometric laser microscopes. (Fun.) Back in the day, I made a nulling-type phase digitizer at 60 MHz by driving a phase shifter with a 12-bit DAC (AD-DAC80), and wrapping a 13-bit successive approximation loop round it (AM2904 with an extra flipflop). With quite a lot ...


another MicroZed project

Started by John Larkin in sci.electronics.design6 years ago 7 replies

Another board: https://dl.dropboxusercontent.com/u/53724080/PCBs/P350_12.jpg The microZed compute platform plugs into the middle. The...

Another board: https://dl.dropboxusercontent.com/u/53724080/PCBs/P350_12.jpg The microZed compute platform plugs into the middle. The application board has eight DAC channels with filters and amps, two ADC inputs, power supplies, BIST, stuff like that. We put some parts under the Zedboard, simple stuff that shouldn't need a lot of probing or anything. The only problem with MicroZe...


Stepper motor, micro-stepping: Left vs Right

Started by Anonymous in sci.electronics.design8 years ago 10 replies

Using 12bit DAC, I would like to have 32 microsteps. I have mounted a laser on the shaft so I can see the laser beam on my wall, where I have...

Using 12bit DAC, I would like to have 32 microsteps. I have mounted a laser on the shaft so I can see the laser beam on my wall, where I have 32 grid lines. I've experimented, and it goes pretty well, all 32 steps are more or less on grid - when I go right. But when I turn back left, the laser dot moves fast, then slow, then fast again - not on grid. I haven't found anything on the ...


cool paper on dithering

Started by John Larkin in sci.electronics.design4 years ago 24 replies

...

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=38&ved=0ahUKEwjG19u1n_TQAhVnrlQKHR UMAEc4HhAWCEgwBw&url=https%3A%2F%2Fwww.cscamm.umd.edu%2Fprograms%2Focq05%2Fadams%2Fadams_ocq05.p df&usg=AFQjCNFFz_m97QqzWywq87nBJJ5uONIk0A&bvm=bv.141320020,d.cGc&cad=rja or maybe http://tinyurl.com/zhlgolz This has some really interesting ideas about extending DAC resolution with scrambled th


Filter Evolution

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

We're working on the FPGA signal processing for The Wayback Machine. This is a box that stores user-supplied waveform files and plays...

We're working on the FPGA signal processing for The Wayback Machine. This is a box that stores user-supplied waveform files and plays them back at some programmable rate. If we use a DDS clock to determine the playback sample rate, and dump the file data into a DAC, we get the obvious stairsteps in the data, at the sample rate SR. A sine wave at frequency Fs, which was sampled at, say,...


another fast-ramp current source thing

Started by John Larkin in sci.electronics.design8 years ago 9 replies

https://dl.dropbox.com/u/53724080/Circuits/Isrc_5.JPG R5 and the dac thing can be replaced with a bandgap if the ramp slope doesn't need to...

https://dl.dropbox.com/u/53724080/Circuits/Isrc_5.JPG R5 and the dac thing can be replaced with a bandgap if the ramp slope doesn't need to be calibrated. -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Cust...


4quad supply

Started by John Larkin in sci.electronics.design4 years ago 71 replies

I'm designing a gadget that will need a bunch of 4-quadrant (+- voltage, source/sink) power supplies, DAC controlled, well bypassed on the...

I'm designing a gadget that will need a bunch of 4-quadrant (+- voltage, source/sink) power supplies, DAC controlled, well bypassed on the output. Range is roughly +-12 volts, 100 mA or so. So I need a power opamp that doesn't mind a capacitive load. We have TCA0372 in stock, a dual 40-volt, 1 amp opamp that costs 45 cents. Great part. I set one up. It really, really doesn't like cap...


conditioning a fast current-out DAC

Started by John Larkin in sci.electronics.design4 years ago 4 replies
DAC

Fast DACs usually have differential current outputs. Properly converting that to a clean single-ended signal is a little tricky. This looks...

Fast DACs usually have differential current outputs. Properly converting that to a clean single-ended signal is a little tricky. This looks good: https://dl.dropboxusercontent.com/u/53724080/Circuits/Fast_Stuff/V377_DAC.JPG The AD8130 is a cool amp. It has two differential inputs and the output is the sum of the two diff inputs. (One gotcha is that the inputs are only linear up to 2 ...


Waveform interpolation

Started by bitrex in sci.electronics.design5 years ago 50 replies
DAC

Suppose I have some sampled signal data in a ROM on a microcontroller or something, and I'm reading it out to a DAC. Let's say that for some...

Suppose I have some sampled signal data in a ROM on a microcontroller or something, and I'm reading it out to a DAC. Let's say that for some reason, I'd like to begin reading this data at some random position, go for a while, and then stop at a random stopping point and jump to another random position in the ROM and continue reading, and so on, to obtain pseudorandom variations on the w...