Finally, after earlier setback, I’ve got the amplifier and 4-inch speaker working properly. I tried multiple setups today and managed to get rid of the distortion. The book dictates 9V, 33K resistance on audio input. This results in my case in a temperature of 90 degrees (194 fahrenheit). Which is uncomfortably high. I therefore decreased […]
This experiment of Make: Electronics demonstrates the use of self-inductance and capacitance in audio filtering. The low and high frequencies of the audio signal can be separated and send to different speakers (woofer and tweeter). The audio chip used for this experiment is the TEA2025B, a somewhat older chip that was used in portable radio […]
I finally finished the Darth Vader voice changer this weekend. I took a belt with two snap hooks from an old bag. Next I fitted the box with the voice changer with two black screw eyes that were large enough for the snap hooks. The enclosure is now comfortable around the neck of a child. […]
I received 50 TEA2025B amplifiers over the mail today. I ordered these IC’s about two weeks ago at Aliexpress.com. Aliexpress is an affiliate of Alibaba. I have never ordered components from Aliexpress before and I was curious to see how they would perform. Eager to get my hands on these OpAmps I quickly unpacked but […]
After making an improvised coil (experiment 25) and cutting a coil out of a speaker (experiment 27) in this experiment the self-inductance of a coil is demonstrated. As a coil in this experiment I used 44 meters of coated copper wire on a spool. In parallel with the coil two low current LED’s are connected. […]
I couldn’t get the cylindrical neodymium magnet of the required size so I skipped experiment 26. Next experiment 27: Loudspeaker Destruction of Make: Electronics is a very simple and very short experiment but worthwhile nevertheless. It demonstrates how a loudspeaker works by literally cut it to pieces. Luckily I had an old 2 inch speaker […]
About a week ago I wrote about a Darth Vader voice changer that I am making. I finally have finished a prototype but not without problem. I soldered all the external components to the Velleman MK171 kit. When I tested the circuit I discovered that three red push-buttons (see images below) weren’t functioning. I disconnected […]
I skipped experiment 24 of Make: Electronics. The reason is that I’m not really interested (at least not right now) in completing the Intrusion Alarm. I do appreciate what the author of the book, Charles Platt, is trying to achieve. He gives a couple of good hints for upgrades of the Alarm without presenting the […]
First part in a series how to make a Darth Vader voice changer with the HT8950 chip.
I have a lot of tools laying around in a big tool box. The problem is that whenever I need a tool I always end up searching for it. I decided it was time to make a proper tool board. I bought some cheap board (61 x 123 cm). I had some pine wood (9 […]