4 ms·

the discrete hardware part of the Apple II is fascinating window into 1970s hobbyist electronics sometimes. In the flashing text mode, you might think the flas

by deater 2y ago

the discrete hardware part of the Apple II is fascinating window into 1970s hobbyist electronics sometimes. In the flashing text mode, you might think the flashing text (also used for the cursor) is done in software or something. But no, it's a 555 timer gating off the video signal for that particular character.

byteknight 2y ago
This reminds me of when my grandpa told me the clicking we hear when we turn on a turn signal is from the old days when a cover used to visibly/audible "click"/close over the light, mimicking a blinking effect.
- rbanffy 2y ago
  I always thought it was one of the many relays under the dash.
- sjsdaiuasgdia 2y ago
  I think your grandpa was messing with you. Flashing turn signals and the click sound came with a 1938 invention which Buick started putting into cars in 1939. There were other turn signal approaches used before then, though not all cars had turn signals. Some of those approaches were mechanical, but still don't really align to your grandpa's claim. https://www.qualityplusautomotive.com/blog/2020/september/the-unmistakable-click/ https://www.qualityplusautomotive.com/blog/2020/september/th... https://www.cartalk.com/blogs/jim-motavalli/strange-true-history-turn-signal https://www.cartalk.com/blogs/jim-motavalli/strange-true-his...
- Dwedit 2y ago
  There's a video by Technology Connections all about turn signals: https://www.youtube.com/watch?v=2z5A-COlDPk https://www.youtube.com/watch?v=2z5A-COlDPk Demonstrates thermal-based flashers as well as capacitor-based flashers. They are clicking because metal is moving and hitting metal.
  - justsomehnguy 2y ago
    I think these links should be labeled with NSFDAPFAW (Not Safe For Doing Anything Productive For A While)
  - MarkusWandel 2y ago
    Only skimmed the video, but did he get into why even the most modern cars, festooned with CanBus controlled light modules and LED almost everywhere, still have incandescent bulbs in the taillights? I'm pretty sure I've even seen those on electric cars. Once upon a time, an "accidental" feature was that the thermal bimetallic flasher modules would flash much faster if the load was lower. So if you turn indicator flashed fast, you knew that one of the bulbs was out. I've seen this fairly recently; is it "designed in" to modern turn signal systems even though the bimetallic flasher units are long gone? And is that why there's still an incandescent bulb back there - because it's the easiest to monitor for not being functional by just watching the current draw? Also once upon a time, you could pull out the thermal bimetallic flasher unit and replace it with an "electronic" one consisting of a transistor, a couple of passives, and a relay. Those made a very satisfying loud "CLICK CLACK" kind of noise that was impossible to miss. In my modern, car, I'm pretty sure the tick tock sound is synthetic, but it's also quiet enough that, at least at my age, it's easy to miss.

by deater 2y ago

byteknight 2y ago

This reminds me of when my grandpa told me the clicking we hear when we turn on a turn signal is from the old days when a cover used to visibly/audible "click"/close over the light, mimicking a blinking effect.

rbanffy 2y ago
I always thought it was one of the many relays under the dash.
sjsdaiuasgdia 2y ago
I think your grandpa was messing with you. Flashing turn signals and the click sound came with a 1938 invention which Buick started putting into cars in 1939. There were other turn signal approaches used before then, though not all cars had turn signals. Some of those approaches were mechanical, but still don't really align to your grandpa's claim. https://www.qualityplusautomotive.com/blog/2020/september/the-unmistakable-click/ https://www.qualityplusautomotive.com/blog/2020/september/th... https://www.cartalk.com/blogs/jim-motavalli/strange-true-history-turn-signal https://www.cartalk.com/blogs/jim-motavalli/strange-true-his...
Dwedit 2y ago
There's a video by Technology Connections all about turn signals: https://www.youtube.com/watch?v=2z5A-COlDPk https://www.youtube.com/watch?v=2z5A-COlDPk Demonstrates thermal-based flashers as well as capacitor-based flashers. They are clicking because metal is moving and hitting metal.
- justsomehnguy 2y ago
  I think these links should be labeled with NSFDAPFAW (Not Safe For Doing Anything Productive For A While)
- MarkusWandel 2y ago
  Only skimmed the video, but did he get into why even the most modern cars, festooned with CanBus controlled light modules and LED almost everywhere, still have incandescent bulbs in the taillights? I'm pretty sure I've even seen those on electric cars. Once upon a time, an "accidental" feature was that the thermal bimetallic flasher modules would flash much faster if the load was lower. So if you turn indicator flashed fast, you knew that one of the bulbs was out. I've seen this fairly recently; is it "designed in" to modern turn signal systems even though the bimetallic flasher units are long gone? And is that why there's still an incandescent bulb back there - because it's the easiest to monitor for not being functional by just watching the current draw? Also once upon a time, you could pull out the thermal bimetallic flasher unit and replace it with an "electronic" one consisting of a transistor, a couple of passives, and a relay. Those made a very satisfying loud "CLICK CLACK" kind of noise that was impossible to miss. In my modern, car, I'm pretty sure the tick tock sound is synthetic, but it's also quiet enough that, at least at my age, it's easy to miss.