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jc2048

Solar Garden Light

Posted by jc2048 Mar 31, 2017
A couple of days ago, I was in a store here in the UK (in the garden department looking at seeds and bulbs) when some 'solar lights' caught my eye. The very cheap ones didn't look up to much, but the £2 ones had a decent solar cell on them so I bought one. I was curious as to how something with a CE sticker saying it had a 1.2V battery inside was able to light a white LED that would need a forward voltage of around 3V to illuminate.   Here are some photographs as I disassembled it. ...
This one is similar to what I did with the gain, except that this time I kept the base current constant and measured the collector current in relation to the collector-emitter voltage. I reworked the original test circuit, which is how this blog follows the last one so quickly. As before, I'm looking at an NPN bipolar junction transistor (a 2N3904) and the situation where the emitter is the common terminal between input and output.   Here's the circuit (minus decoupling caps):    ...
Another 'Transistors' blog. I thought this one would be easy, but it turned out to be quite challenging and, in some ways, a bit of a failure.   The current gain of a bipolar junction transistor (when the emitter is the common terminal between input and output) is the ratio of collector current to base current. In some ways, it's the most fundamental parameter that the transistor has, because our simplest conceptual model of the device is something that takes an input current and p ...
Part 1 can be found here:   PID on a EK-TMC4C123GXL Evaluation Board. Part 1: Getting started.   At this point I had to decide what to try and control. I wanted something that would be slow enough that the processor could keep up, but fast enough that it would present at least some kind of a challenge. In the end I decided to do that most traditional of things, the one that everyone does with a new processor board, I'd light an LED. Here's the LED     it's a 1W warm whi ...
When jancumps introduced us to the PID library (link below) I said I'd have a go with it, since I had a TI evaluation board (an EK-TMC4C123GXL with a Tiva TM4C123G on it), wanted to learn a bit about ARM coding, and thought that running a control system with a processor in the loop sounded interesting and a bit of a challenge, but it's taken me a while to get started, what with the transistor blogging and everything.   MSP432 and TI-RTOS: PID Library Part 1 - Intro   First aim is ...