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Hi matencio,

What configuration do you intend to build? The whole installation for a carnival stall as shown in your photographs, i.e. 18 flipper tables to control 18 horses, plus the big light display? Or just a small single-player version? (Playing alone or maybe against a computer?)

If I were to build this, for one or a small number of players, I would have a strong inclination to use actual stepping relays. They can be bought on ebay for $50 to $100 apiece; 25 positions seems to be a common version. Nothing like the clicking, clacking sound of an actual mechanical stepper! ;)  Add "real" switch contacts, and either light bulbs or LEDs to taste...

On the other hand, if you want to build this for a larger number of players and actually deploy it for routine use, the stepping relays may become a cost and reliability challenge. In that case, a microcontroller-based implementation is probably the more pragmatic approach. You will need to add hard-wired multiplexing logic to read a large number of switches and drive an even larger number of LEDs, however!

I think I'm going with the second version using an Arduino Uno (hopefully I can figure out how to program it). I'm not building for 20 people, just four or maybe six. Small but I'd like to be able to increase the number if I changed my mind later - like from four to six or more. As I said, this is more for family to play on and me to learn about electronics and even the Arduino I have.

As much as I would love those clanking, thumping step relays, the cost is prohibitive. So that makes the choice easy. The micro-controller-based implementation is intimidating for my lack of experience. Thanks, I think this is on the right path though.
I can also suggest the PCB route. If you keep the copper pours it acts as a nice shielded cover to boot, and the one color printing is included in the price ;)
General Chat / What is this scope and is it worth picking up?
« Last post by primegaps on Today at 02:50:03 PM »
I found this scope in an electronics disposal.
it has always been a goal of mine to find a scope with a round crt display, it just seems so retro.
This is an old tektronix scope, but that's all i know. I dont think i can add it to my collection because it is HUGE and has a separate HUGE power supply.

Anyone know anything about this scope?  Is it worth saving?

Test Equipment / Re: Handheld meter electrical robustness testing.
« Last post by bitseeker on Today at 02:49:10 PM »
I need to write Revlon a letter explaining I am a dissatisfied customer

That'd be a hoot :-DD
Projects, Designs, and Technical Stuff / Decapping a MOSFET
« Last post by blueskull on Today at 02:48:32 PM »
I posted another thread about getting silicon MOSFET dice with no practical solution found yet.
Therefore, I decided to use SiC devices, and I've already designed accordingly.
However, out of curiosity, I just want to see what if I can get dice from packaged devices.

I decapped a Toshiba TK32V60X MOSFET (from its 8mm*8mm DFN package), and the result is here.
During the process, acid etched bonding wire and permeated through bonding pad, leaking into die internally, and created discoloration.
I haven't tested those bare dice yet, but I bet they won't work properly, and even if they work, I won't be comfortable to apply 400V to it.
So the question is, is there a good way of decapping copper wire bonded silicon power devices?

I used 3:1 mixture of 98% H2SO4 and saturated NaNO3. Apparently this stuff is not as good as real HNO3, but buying HNO3 is too expensive, I don't want to spend $50 on its shipping.
I used a 200C hot plate to decap the chip, the chip lies on hot plate, pads side down, marking side up, and I applied acid mixture drop wise and cleaned foaming using the side (not tip) of a pair of tweezers.
It took about 20 minutes to reveal the die, I then cleaned it up a bit using IPA, then desoldered the die from its copper substrate. I did another cleaning and shot the photos.
Beginners / Re: Why so many ferrite beads in Meanwell AC/DC power brick ?
« Last post by Dago on Today at 02:40:38 PM »
These power supplies tend to use 1-layer PCBs which is not a great starting point for a design which should pass EMC tests. The ferrite beads are to work around that. They are cheap.
Test Equipment / Re: Only 7 bit vertical resolution on scope?
« Last post by Octane on Today at 02:35:22 PM »
It is using all 8 bits. If you shift your waveform down horizontal it is done still in the analog domain in the frontend by offsetting the voltage before the ADC. I think usually the full scale of the ADC should be the 8 or 10 vertical divisions (however many your scope has). I think in some scopes there are two hidden divisions outside the top and bottom of the screen, but nevertheless the 256 steps are always scaled more or less to the screen. I hope this answer makes sense.

General Chat / Re: Scope power cord
« Last post by Monkeh on Today at 02:30:00 PM »
Yep, you can get C13s in the full set of up, down, left, and right angle. You'll pay for it, but you can get 'em.

StayOnline there aren't cheap, but I've used them before, quality seems okay. They'll make pretty much anything you like to order if they don't already stock it (no up or down angles to order, though, guess they don't have the moulds).
General Chat / Re: Scope power cord
« Last post by rdl on Today at 02:27:32 PM »
Up angle, eh? Sure enough, that's exactly what I've been wanting. Thanks for the info.
900 MHz SRF
[email protected]

Looks like you should widen your search to 22nH and 27nH more common values.
Particularly 22nH + some tracking or parasitics would easily yield 24nH or over.

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