Sprucing up an old scope: fixing the dials on the Owon SDS6062V

Sprucing up an old scope: fixing the dials on the Owon SDS6062V

  January 01, 2025    Tahmid

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I got the Owon SDS6062V scope back in 2014 when it seemed a great deal compared to brands like Tektronix and much better than cheaper analog or portable digital scopes. These days, I've been using the Rigol DS1202 for hobby projects which is a better part, in my opinion. Of course, none of these are as nice as the Keysight MSOX scopes at work.I've demonstrated the Owon scope in previous projects such as Generating complementary PWM with adjustable deadtime for...

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Insights from repairing a 30V 5A power supply (BPS-305)

Insights from repairing a 30V 5A power supply (BPS-305)

  December 31, 2024    Tahmid

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When I started working on a project (hopefully more on that soon), I reached out for an old 30V 5A power supply (Lavolta BPS-305). I rotated the voltage dial to try to get to 24V and observed that the voltage would not go past 15V, even though it is rated for 30V. Even though this supply was a few years old, I had not personally used it before. So, it wasn't clear whether it was a previously-functioning supply that stopped working, or whether it was always broken.Fig....

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A low-cost high-side current sense amplifier: design considering non-idealities

A low-cost high-side current sense amplifier: design considering non-idealities

  July 10, 2024    Tahmid

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Current-sensing is commonly used in power electronics and embedded systems, both for system monitoring, as well as to take decisions. Examples of common use cases for the latter are:Monitoring inductor current for current-mode control in power convertersMonitoring converter current for overcurrent protectionReading battery charge current to inform the charging processReading output current to compute output power to inform how to proceed in an MPPT charge controllerUse...

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Generating complementary PWM with adjustable deadtime for the RP2040

Generating complementary PWM with adjustable deadtime for the RP2040

  July 03, 2024    Tahmid

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I have previously discussed the benefits of using the Raspberry Pi Pico, leveraging the easy-to-program Micropython along with the capable hardware peripherals: 2023 Updates: PhD; Pi Pico and Quick and dirty PIC16F72 programmer with the PicoSeveral articles in the blog have previously described applications of PWM in embedded systems, such as Stereo audio player using the PIC32, MCP4822, microSD card and the MDDFS library, DC motor control with...

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Electrolytic caps over frequency: why is my 470uF actually 20uF?

Electrolytic caps over frequency: why is my 470uF actually 20uF?

  March 23, 2024    Tahmid

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While using an LCR meter to measure a 470uF cap in lab, the meter read the expected values at low frequency (100 Hz). But when measured at 100 kHz, the meter read 19uF. While I expected a capacitance drop due to parasitic inductance, I was still surprised at this sharp of a drop. I decided to dig further.Simplistically, we can model a real capacitor as the following circuit:Simplistic capacitor model including parasitic elementsC is the main capacitor and the other...

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Quick and dirty PIC16F72 programmer with the Pico

Quick and dirty PIC16F72 programmer with the Pico

  January 02, 2024    Tahmid

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Accompanying Github repo: https://github.com/SyedTahmidMahbub/q-dpico_picprog72Having come to Dhaka over winter break, I was able to scrounge through the 10+ year-old collection of electronics stuff my parents had in storage from when I would experiment with electronics during the initial days of this blog. Among the many parts, I stumbled upon a large number of PIC16F72 MCU's - the defacto 8-bit cheap MCU of choice for many (commercial) projects. However, I couldn't...

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