| Electronics > Projects, Designs, and Technical Stuff |
| DIY Modular Test Equipment Project |
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| void_error:
Oh, hi there! If you scroll down you might realize I've been consistently biting off slightly more than I can chew. What started off with me trying to design and build myself a proper bench power supply has grown into a small collection of bits of test equipment being designed as functional modules sharing a common communication bus which is yet to be named. There is no set date for completion of anything as I'm doing this in my spare time and don't expect regular updates. Since I'm stubborn and I've put a lot of time and effort into this I'm not going to abandon it and I've learned a lot so far. Enjoy! Almost forgot... UPDATES below. UPDATES 2018.02.25 First draft of the UI is now on GitHub. Check the draft branch of the repo. 2018.02.26 First draft of the Waveform Generator + Frequency Counter module is up on GitHub. Repo here. 2018.02.27 First draft of the Regulator for the Digital part is also on GitHub. Link to the repo. 2018.02.28 First draft of the Regulator for the Analog part is also on GitHub. Here's the link to the repo. Damn, too many firsts :P 2018.03.04 Finished the PCB layout for the UI and yes, it's rev.0 again. Some MCU pins were moved around. It probably won't be the final version as some tweaking is still required. 2018.11.25 Updated everything. Switched to STM32F101 MCUs. 2019.12.27 Waveform Generator is now almost finished. |
| void_error:
User Interface This is the control panel shared by all the different modules. I tried to keep it as basic as possible, as well as easy to use. Nothing too fancy here. User accessible features: * 128x64 2.8 inch monochrome LCD display - ERC12864-655 * 4 square push buttons, backlit, function displayed on LCD - Omron B3W-9 * 2 pushable quadrature encoding switches * Buzzer, in case you want those annoying beeps, can be turned off * USB connectivity via a USB-UART module, initially as USB-serial device, planning to include SCPI commands * Bootloader for relatively easy firmware updates Specs: * DC input: 5V (3.3V onboard LDO) * Optional fan control/monitoring pins * Microcontroller generated synchronization signal, used to synchronize DC-DC converters (SYNC) * Microcontroller clock output (BUS_CLKR) * Off-board connector (2x10 pin IDC) for communication with other modules via 1-wire, I2C, UART Hardware: * STM32F101VC * EEPROM for saving calibration data and presets * more details coming soonTM USB-UART module * No idea anymore, could be anything * SiLabs digital isolators on the UART side |
| void_error:
These two are going to share the same PCB Waveform Generator Features/Specs: * Sine wave / Triangle wave output - 0.1Hz - 10MHz for sine, 0.1Hz - 250kHz for triangle * Adjustable amplitude (up to 10VPP @ 50ohm) and DC offset (-5V...+5V) * Square wave (uses DDS chip) / PWM output (from UI MCU or local MCU) adjustable output level, frequency values for the PWM are limited by the capabilities of the User Interface MCU or local MCU * Output driver with adjustable current limit for Sine / Triangle Hardware: * AD9834 DDS waveform generator chip * AD603 Variable Gain Amplifier * LMH6321 output driver (sine/triangle only), adjustable output current limit * REF2041 dual output voltage reference * [https://www.analog.com/media/en/technical-documentation/data-sheets/ad5761_5721.pdf]AD5721[/url] 12-bit DACs for setting offset & amplitude Frequency Counter Features/Specs: * 100MHz maximum input frequency * Adjustable input trigger level * Selectable divide by 10 or by 1prescaler * External 10MHz clock reference input Hardware: * STM32F101RC * LMV7219 high speed comparator * MCP41050 digital potentiometers * glue logic |
| void_error:
Modular DC Electronic Load[OUTDATED] Features/Specs: * 200W maximum continuous power dissipation per module depending on the cooling used, calculations were done using one cheap desktop CPU heatsink for each two MOSFETs * Two ranges: 50V maximum @ 4 A or 12.5V @ 16A - not a final spec, subject to change * Fan Control via the Aux Digital Power Board * Overtemperature protection * Overvoltage protection * Overcurrent protection * Optional on-board microcontroller for the "smart" load configuration * Two modules can be connected together to make a 400W load - subject to change (it's quite tricky to implement) Hardware: * DAC: AD5662 * ADCs: AD7683 * LM56 temperature sensors in thermal contact with each MOSFET * LM4132-4.1 4.096V reference for DAC and the ADCs * 2 IRFP460 N-channel MOSFETs as current sinks * A bunch of op amps (see schematic) * PIC16F1619 optional microcontroller for the "smart" load configuration, will use the PID loop of the Math Accelerator module for Constant Voltage/Resistance/Power functions * Dirt cheap AMD CPU cooler |
| void_error:
Bench Power Supply[OUTDATED] Features/Specs: * Configurable for different output voltages, output currents and number of channels * Two current ranges * Overtemperature protection * Overvoltage protection * Overcurrent protection Hardware: * DACs: AD5662 * ADCs: AD7683 * LM56 temperature sensors in thermal contact with each post-regulator BJTs * LM4132-4.1 4.096V reference for DACs, ADCs and OTP circuit * A bunch of op amps * It can be built with or without digital control |
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