GreenPhotons

Temperature measurements with an NTC thermistor

Post author:uwezi
Post published:2020-03-23
Post category:AVR Electronics Everything Science
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Following a discussion on Facebook I put here an online tool to calculate the output of a voltage divider consisting of a fixed resistor and an NTC thermistor following a first order Steinhart–Hart equation.

The calculations are based on a voltage divider where either the voltage over the NTC or over the pass resistor is measured. You can change the values in the script according to your own settings. If you break the script for some reason, just reload the page.

SageMath uses Python as programming language.

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Not WormFood’s AVR Baud Rate Calculator

Post author:uwezi
Post published:2019-11-17
Post category:AVR Computers Electronics Everything
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This page without a frame: https://sciencetronics.com/uwezi/avrbaudrate.php

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0.5 mm pitch FPC breakout board - soldered

Some Toner-Transfer PCB Highlights

Post author:uwezi
Post published:2019-05-12
Post category:Electronics
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Some recent highlights from my home-made circuit boards using the toner-transfer method. 0.5 mm FPC breakout board Yes, I have been told that I am crazy before... Designed in KiCAD…

Canvas: Using Python to create Calculated Questions

Post author:uwezi
Post published:2019-05-11
Post category:Everything
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Background I just recently started with Canvas because Uppsala University has decided to use it as its upcoming LMS platform after a failed attempt with another product. Therefore I had…

A tiny watchdog

Post author:uwezi
Post published:2018-12-06
Post category:AVR Computers Electronics
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In a recent quick-and-dirty project with a Wemos D1 mini clone I had some problems with the reliability of the code. The ESP8266 contains two watchdogs which have the sole…

IKEA TRÅDFRI Zigbee module on a breadboard.

Hacking IKEA trådfri lighting automation

Post author:uwezi
Post published:2018-11-04
Post category:Computers Electronics Everything LEDs
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I recently visited IKEA again and got interested in their affordable line of home automation/LED lighting products called TRÅDFRI (meaing wireless in a play-with-words kind of Swedish). Of course there…

project update: a TTL/CMOS computer

Post author:uwezi
Post published:2018-10-15
Post category:Electronics
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Exactly one month later – our electronics course at Uppsala University just approaches its end – and I got the next shipment for my new project: 1.1 km of equipment wire.

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twenty new breadboards

new project: a TTL/CMOS computer

Post author:uwezi
Post published:2018-09-15
Post category:Everything
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Watching Ben Eater’s youtube series on his breadboard computer based on discrete logic chips inspired me to pursue my own construction. Apart from a lack of time I also needed some more breadboards, which arrived today.

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A visitor on the balkony

Post author:uwezi
Post published:2018-02-26
Post category:Everything
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Unschlagbares Angebot der Firma Elektor.

Top deal of the week?

Post author:uwezi
Post published:2017-06-13
Post category:Electronics LEDs Politics Science
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Today I received a newsletter from the publisher Elektor. I am offered a special deal on a Peltier power generator which can power an LED light from a small candle. And this for an astonishing price of €99.95 instead of the normal price of €119.95.

I’ll have to buy this – or wait a second…

I know the IKEA LED light Jansjö from the add quite well, so I thought until I noticed that this was an USB rip-off from the same series:

IKEA Jansjö spot light: 3 W power, 88 lumen
IKEA Jansjö USB: unknown power(ca 0.5 W?), 10 lumen

We can supply an LED light with probably 0.5 W and 10 lm from the heat of a candle, isn’t it great?

If we stay at IKEA we can buy these candles, 24 with a burning time of 4 hours for €0,99. These together could light our LED light for a full 4×24 hours = 96 hours. Thus we get a total of 96 h x 0.5 W = 48 Wh or 0.048 kWh for €0,99. This corresponds to €20 per kWh, about 100x more expansive than electricity from the wall outlet (in Germany) – ignoring the downpayment on the gadget itself.
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