Yearly Archives: 2017

In my previous series about VFD filament driver, I built a power supply based on a few operational amplifiers and a transistors. I actually implemented this design in a fully fledged PCB:   However, the method used is not perfect. I can still see some biasing issues proper to the […]

I am currently designing a big VFD tube IoT thing and when creating the PCB I sent the gerber files to OshPark. They quoted back about US$180. Ouch. OshPark pricing completely breaks down once you start marking a board 4 inches / 10 cm long or above. So to China […]

Lately I have been playing a lot with the amazing esp32. It is an amazing “microcontroller” for makers, and I add quotes to “microcontroller” because really, it’s an IoT do-it-all SoC; all for the low price of about US$5. One of the main features of the esp32 is its ability […]

Final result, driving a IV-25 VFD tube! If you haven’t yet, please read the part 1 and part 2 of building a VFD filament driver!   The board PCB came back from Osh Park within 2 weeks, and I quickly put it together after getting genuine LP2985 voltage regulators (previous […]

This is a sour experience I wish to share with everyone. The lesson learned: do not buy ICs from Aliexpress/Banggood etc. On my VFD tube driver design, everything runs off 12V. Everything except an ATTINY13 that generates a 5V square wave. I therefore needed a tiny 12V to 5V drop […]

There are many different kind of ESP32 boards out there; but the DOIT is by far the most popular one. It’s simple: if you type ESP32 in Banggood, Aliexpress or Taobao, it is the first design that comes up.   Quite simply, if you are starting with ESP32, it is […]

As part of the process of building a VFD (vacuum fluorescent display) filament driver, I use an ATTINY to generate a square wave signal. I program these chips using an Arduino Uno used as a programmer through the “Arduino as ISP” sketch. This process is painfully slow. Every time you […]

OSH Park is a PCB manufacturer tailored to hobbyists. They take orders for very small quantities of boards (minimum 3) and they are able to do this by taking small hobbyist projects and compiling them into a big batch. A typical two layer board costs US$5 per square inch.   […]

In my previous post, I showed how to build a square wave floating above ground using an operational amplifier. I originally did my test at 5 Khz, which worked quite well but gave a nasty humming sound. The signal must therefore be above the hearing range; and I have settled […]