Project: Police Flasher and 7-Segment LED Clock Through-Hole Soldering Kits | Hacker News Reader

Project: Police Flasher and 7-Segment LED Clock Through-Hole Soldering Kits

goughlui.com

51 pointsjandeboevrie19 comments

This brought back a great memory for me. When I was very young, less than ten years old, my dad would bring home little kits like this from work in a little cooler that was his lunchbox. He started with the most simple ones that did not require solder, and worked up to more elaborate kits. We would work on them in the basement shop together. He let me mess up, and let me explore and experiment. This was the early 80's, and we powered these little kits with a DC power supply that he had built...from a kit.

Great memory that I had forgotten. My dad died in February of this year after a long struggle with pulmonary fibrosis. He could fix anything. He could build anything. With these little kits he taught me so much. Thanks for the memory!

Ugh, condolences, but what a great dad you had!

Thank you.

My 6 year old just got very interested in a very basic electric kit, but he more or less exhausted its possibilities. I am trying to forge a path forward, maybe with switches on a breadboard or something. What are electric kits that do not require solder?

The very first kit I remember was housed in a metal project box about the size of a large dictionary. This was the early 80's or possibly the late 70's. I was very young at the time, but I still remember it fairly well.

The heavy box was open on the bottom, and contained a homemade DC power supply (transformer, voltage rectifier, etc) to power the "project area" on top of the box. The project area contained 3 different-sized breadboards, maybe two dozen red and green LED's, some sort of buzzer, a couple of toggle switches, and a push-button switch.

Dad supplied me with some wire (with stripped ends). I could place one end of the wire into a slot on the breadboard, and connect it to another location, and then manipulate the switches/buttons to either light up an LED or cause the buzzer to buzz...or both. This may sound simple and boring, but to me it was pretty awesome.

Years later, when I was in middle school, I made a homemade project that would deliver a harmless, but painful electric shock to my friends fingertips. It was nothing more than a transformer, a push-button switch, and a battery, mounted in a small box. On top of the box were two square metal pads that I had cut from an old Crisco can. My victim would place their index and middle fingers onto the two metal pads while I pressed and released the switch.

I love the look of 7-segment displays. If you want one that is WiFi controlled via an ESP32, check out my blog post: https://willem.vooijs.eu/posts/cute-astronaut3/

I remember the time when we only had red, green, and orange LEDs. Blue LEDs were a real game changer.

https://www.nobelprize.org/prizes/physics/2014/press-release...

I wish the article had some links to these kits. I have been trying to find the police flasher one and all I seem to find is cheap ones with only a few leds. Anyone know where I can find the police flasher? Thanks

I too am interested in finding some kits as I recently started soldering and wanted to practice using some kits as it sounds more fun than just practicing on a breadboard.

One site I found while watching a YouTube video was: https://www.electronickits.com/ but I haven't ordered anything yet and really don't know much about them besides they were listed in a video...

I don’t know the vendor you linked either, but Digikey (a huge electronics parts wholesaler) has an entire educational kits section on their site: https://www.digikey.com/en/products/filter/educational-kits/...

Lots of microcontroller stuff in there, but also plenty of simpler hardware electronics projects

Aliexpress has them, eg.: https://www.aliexpress.com/item/1005003457635092.html

The pcb looks very similar, but is missing the holes to break the light parts away (probably saving money on the drilling).

> AT89C2051

This damn chip will never die, will it?

Both projects seem simple enough to make with your own KiCAD custom board, and with Digikey Red at just $5 for small boards, and with modern miniature parts (wow, lots of big through hole stuff in this kit), it's probably cheaper than you think to make your own custom parts.

I think these days, I'd make a surface mount beginner board with SOIC (relatively large surface mount) chips and maybe 0805 (imperial) resistors. Modern electronics are often with much smaller parts like BGA or VQFN leadless and 0201 resistors.

But staying with larger SOIC (half the size of DIPs) is still fine enough for beginners and surface mount skills probably are more important today.

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It probably should be noted that 4-character LED modules are cheap and common. This project uses 3x 2-character LED modules to display "hours:minutes:seconds", but I think the typical "hours:minutes" display is easier given off-the-shelf equipment.

Lots of turn key manufacturers out there too. JLPCB will take your proto board files and mail you the whole thing soldered and ready to go in a few weeks. If you use relatively common parts you won't need to solder anything at all.

The police flasher, with a 555 timer and a decade counter to get the classic police effect, is a thing of the past. These days you'd put in a microcontroller and program in the desired sequence. I don't know which is better, but that's how the world is.

That requires two skillsets, the electronics part only one.

Depends on your goal. If you really just want a blinking thing, maybe buying a ready-made one is better, or alternatively building the one you find easiest. If you want to make a product, whatever maximizes profit is better. If you want to learn about microcontrollers, build it with microcontrollers. If you want to understand how 555s and RC charge/discharge curves work, build it with a 555.

A friend asked me to make a brake and turn-signal controller for a custom motorcycle. I started with 555s until I realized I could get an ATTiny for less money and add more features at the same time.

The funny part is that in terms of raw part cost, the microcontroller is likely cheaper.

I was just dabbling and saw that a 7 segment hex decoder chip was, like, $8 or $9 but a Raspberry Pi Zero was $5.

Makes one rethink the issues involved.

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