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I bought this Tek 453A on eBay from Germany for a super affordable 1900 CZK (around 84 USD), making it an irresistible purchase. Upon receiving it, the scope was in great shape (almost brand new). I will use this scope a lot in my analog RF projects. Anyways, the inside is so beautiful, basically a work of art, so I decided to post it here. submitted by /u/A55H0L3_WindowsXP [link] [comments]

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🎥 Спільний українсько-естонський проєкт щодо розвитку підприємництва та туризму у громадах kpi сб, 05/10/2025 - 21:19

🎥 КПІшники — вдруге чемпіони України з шахів серед студентів! kpi сб, 05/10/2025 - 21:08

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My 555 timer(up) in astable mode My flip flop D(down) done with logic gates submitted by /u/White_Septendecim [link] [comments]

My multimeters (generic DT-9205A) 9V battery died. So, I tried to replace the 9V battery with a single 18560 rechargeable battery (3.7V). I connected the battery to a small charging/protec board (TP4056), then connected the output of that to a step up converter (MT3608) (to step up the batteries 3.7V into 9V). Finally, i connected the output of the step up converter to the positive and neg of the battery terminals of the multimeter. The Problem: The multimeter doesn't turn on :0 , after some measuring with a simple LED tester, it seems: Battery gives 4Volts Charger/Prot outputs 4Volts Step Up outputs 0Volts Also, when i measure the voltage at the Vin+ and - of the step up i read 0 Volts I tested the circuit (batt+charg/prot+stepup) alone before connecting it to the multimeter and it was functioning normally, giving 9V. Here are some images of the stuff. submitted by /u/Jolly_Ad717 [link] [comments]

Uviquity of Raleigh, NC, USA (a venture-backed start-up pioneering wide-bandgap integrated photonic disinfection technologies) has emerged from stealth after a $6.6m seed-funding round led by Emerald Development Managers (an early-stage venture capital firm specializing in deep tech) with participation from AgFunder and MANN+HUMMEL (specialists in food and agriculture venture capital and advanced filtration solutions, respectively)...

We took a family trip with our grandsons to the New York Transit Museum in Brooklyn, NY. Retired subway cars were on display, some of them seemingly not that old while others dated way, way back. Visitors could freely roam in and out. I was in this one car that had been in service in 1903 which meant it predated the advent of electronics. Even the vacuum tube had not yet been invented by then.

I noticed the passenger area’s bare light bulbs and got really close to one (Figure 1). It was rated at 56 watts and 120 volts. A question came to mind as to how did that car use 120-volt light bulbs when the third rail voltage was (and still is) 600 volts DC?

Figure 1 A subway car light bulb up close showing 56-W and 120-V rating.

When we got home, I tried looking up subway car technical data, but when I came to a wiring schematic, I couldn’t read it. The symbols were indecipherable to me. Only then did it dawn on me that five such bulbs connected in series would be operable from 120 x 5 = 600 volts. If any one of the five were to burn out, all five would go dark, but then maintenance would change all five and discard four good bulbs with the one blown out bulb. It sounded wasteful, but it would have been a practical approach.

Is that the actual truth? I don’t know, and there was nobody on hand to ask, even if I had been quick enough of wit to inquire. Also, I just wasn’t smart enough on site to see if the total number of bulbs in the car was a multiple of five. Maybe one day, I can do that.

Another point about those subway bulbs is that they had left-handed threads on their bases, while household bulbs use right-handed threads. This was to discourage light bulb thefts. Stolen bulbs would not fit into light bulb sockets in households, only into the sockets of subway cars.

John Dunn is an electronics consultant, and a graduate of The Polytechnic Institute of Brooklyn (BSEE) and of New York University (MSEE).

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