Ratti3's Electronics Blog

Arduino Nano 33 IoT Modular Nixie Clock with Web UI USB 5V or 12V, Motion, Light, Temperature, Humidity & Pressure Sensors. NTP Sync, Web Interface for changing settings/time & wifi. Project description The story *** Caution the PSU can output high DC voltages, can cause serious injury *** I'm a bit late to the Nixie Party but I finally made it here. This Nixie Clock is a bit different from the others; it runs using an Arduino Nano 33 IoT, has a motion sensor, light sensor, temperature, humidity & barometric pressure sensor and runs from 5V USB or 12V. It has a web interface for changing settings and syncs the time using NTP. Before I got to the final product, I had spent a lot of time making a Shift Register version with transistors and multiplexing, this worked on the breadboard however I got severe ghosting when I made the PCBs. I gave up and switched over to the HV5530 IC which simplifies things. I had to devour a box of Mr Kipling cakes quickly so I could build the

Experimental tube amplfier project The completed amplifier I decided to make this as I could not find any EF95/6AK5 battery operated tube amplifiers. Also I was bored and fancied a challenge, by the end of this project I had learnt a lot of things, I will now be working on new projects. It seems I can't stay idle for too long.

Alternative to high output voltage transformers The completed module I spent quite a bit of time searching for a high voltage booster schematics, I found some discrete examples and a few based on the UC3843 chip popped up. In the end I decided to settle with the UC3843, as I've seen these chips get used in other tube amplifiers.

Adjustable Li-Ion Battery Level Indicator I needed a lithium-ion battery level indicator for my hybrid tube amplifier project. The goal was to show the battery levels of batteries at once and needed the min/max voltage to be adjustable. After searching the internet for ages, I came across a LM3914 circuit that looked promising, the result came from an image search of LM3914, it appeared to come from an obscure Chinese website which I can no longer find. The circuit diagram was very poor quality and the writing was not in English. So I looked up the LM3914 specs again and noticed different types of circuits in the document and was able to guess some of the component values. The end result was a working battery level indicator based on the LM3914 that was powered from the battery being measured.

Dodgy over discharge voltages The auto activation version I needed a battery protection board for my battery powered tube amplifier, I decided to buy several battery protection boards from Ebay, the reviews looked good and most of the boards seemed very popular. Once I received and tested the boards I noticed a few problems: All of them were using the ABLIC S-8254A IC, but the product code did not match the manufactureres datasheet, this led me to believe these ICs were fakes.

Charging lithium batteries safely Testing the module, 3 18650s charged to 4.18v I needed a PCB module to charge four 18650 lithium batteries for my (battery powered) tube amplifier. I ended up making two different versions of the module, the first design was too compact and got a bit toasty. The second version has more heatsinks and is wider but still reaches 70°C, I could reduce the charge current but decided that if I reduce the supply voltage from 5v to 4.55v, this reduces the max power dissipation by about 0.25W.

Gold plated rear input and output banana sockets. Did I need to make this? Earlier this year I purchased a hybrid EF95/6AK5 hybrid tube amp from Amazon. The make and model was Fosi Audio T20. The amp cost about £70 and is a great little amp for driving loudspeakers or listening via headphones, the input is fed through the tubes and then amplified using a TI solid state amp. So obviously it's not a 100% tube amp but a hybrid one. One thing I noticed is that there is a large amount of DC when turning on the amp, this is not good for the speakers. This can be avoided by flipping the toggle to the off position, however this keeps power to the amp on and it gets slightly warm. Now this being something that is cheap and coming from China, I didn't trust it enough to leave it on like this all the time. So this is when I decided to make a circuit using relays to delay the speaker connection and to add in inline power switch, this meant the power is fed to my circuit as well as the ampl