Sometimes you just need to get a notion about whether a signal is big, little or non-existent, rather than its exact value to 4 decimal places. In my case, I wanted a manometer, so I could tell how much pressure the students were apply by mouth when learning to patch cells. I could also imagine someone wanting to measure the DC value of a voltage that they were applying a digital high pass filter to, just to make sure it didn’t go out of the range of the DAQ. I’ve seen people use cheap multimeters for such task, In this case, I offer a solution, that is perhaps more modular, and certainly cheaper.
I needed to make a little speaker. The real reason? Because of a retro gaming session at work. However, there have been several times that I’ve needed a small cheap speaker that was suitable for delivering simple stimuli. I thought I would post a schematic and take this opportunity to give you an example of how Matlab can make impedance calculations easier, something I’ve talked a little about before.
99% of things you buy from scientific suppliers are violently overpriced. Peristaltic pumps for $2000 that only contain $50 worth of equipment. Homeothermic blankets should only cost about three fifty. But the one that has always annoyed me are syringe drivers. These are nothing more than a stepper motor, a lead screw and a bit of electronics. The budget ones tend to start at around $300, and they go up to ten times that. I’m not standing for that, and neither should you. So I wanted to make one myself.