Recent Posts

1

Projects, Designs, and Technical Stuff / Re: Digital weigh balance - DIY

« Last post by paulca on Today at 01:22:32 pm »

Long shots.

You could tell where the level is in the keg by measuring either the thermal transfer at many points up the vessel, or measuring the sonic properties.  You could possibly even send an electrical pulse through the stainless keg and somehow detect the level.

I could also drill a hole in the lid and mount a laser distance sensor.  However, that involves modifying a pressure vessel with (from memory) 60PSI releif valve and a 100PSI test pressure.  Not something I want to attempt.  Safety first.  A keg lid rupturing is 100% going to be messy.  It could also 1-in-a-million be fatal.

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Projects, Designs, and Technical Stuff / Re: Searching for Decoder/Demultiplexer with Tri-State outputs

« Last post by CaptDon on Today at 01:17:42 pm »

I don't have my Intel book handy but I seem to recall in the days of the 8080A and 8085A Intel had such a device in the 8200 series that did exactly what you are looking for. They developed it for address decoding / sharing and was seen in systems with DMA memory access which required tri-state for the address bus.

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Beginners / Re: Flyback diode on a transformer primary?

« Last post by Terry Bites on Today at 01:16:54 pm »

A snubber is a more suitable remedy

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Projects, Designs, and Technical Stuff / Digital weigh balance - DIY

« Last post by paulca on Today at 01:16:40 pm »

Another one of my project ideas.

"How much is left in the keg?"  It has no level gauges or sight glasses.  When it runs out it's horrible.

Easy... weigh it empty.  Weigh it in situ and tare...

Trouble...  Finding a pressure transducer/load cell which will happily take a 25Kg load 24/7 for a month.

Solution?

Mount the keg on elastic feet.  Buy 4 or 8 feet.  Put empty keg on it, measure distance from base.  Fill keg, measure again.

It should be fairly routine to be able to take both measurements when reseting the keg.  So if the elastic "bumpers" degrade it just gets recalibrated.  If you source different ones, as long as they elastically compatible, it's just a recalibration.

Converting a weight of 2kg - 22kg (for example, a Corny keg) into a distance (even if non-linear) could be done by elastic bumpers, maybe even repurposed suspension "bump dampers".  There are sensors which can measure very small sub milimeter changes in length available cheaply.  Bit of noise filtering and averaging over time should give decent enough for at least a "Fuel guage" type display.

There might be other solutions involving inflated feet.  Many options exist for using a counter-balance, but there is no room for such in a fridge.

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Projects, Designs, and Technical Stuff / Re: Vacuum Fluorescent Display Driver

« Last post by bostonman on Today at 01:16:22 pm »

I agree about things seeming odd and the possibility of multiple issues.

Upon soldering the new IC, I should have measured all the pins to check for shorts. The soldering was done under a microscope and I was confident bridges didn't occur, but anything is possible. With J leads, my limited experience has always been more about trying to get solder between the pin and the pad (which occurred several times while soldering this chip).

Not having activity on the G line (I measured a random G line just to show the signal) I thought could be attributed to the low 38v. Due to the DC/DC getting hot leads me to believe this is the issue to chase, but at some point this weekend (if I have time) I'll remove the board and look around the DC/DC board.

Am I wrong, or is the schematic different than the DC/DC board? If you look at the picture of my DC/DC board I included above, it shows four resistors (or a combination of resistors and inductors) but the schematic shows three (if you include whatever E4 is), also my board has three diodes, and the schematic shows two.

6

Power/Renewable Energy/EV's / Re: 5 out of 6 vendors are scamming people with wrong crosssection of cables

« Last post by 5U4GB on Today at 01:15:33 pm »

    Where were the cables made?   Undersizing of wire and cables made in China has been widely reported on this and other sites.   A lot of the wire is also reported to be made some kind of junk alloy that isn't solderable.  I've learned to not trust the ratings of anything made in China.

Specifically, the most common one you'll encounter is CCA, copper-covered aluminium.  Less common is CCS, copper-covered steel.  Another variant is CCC, copper-covered-copper, where they coat a thin veneer of copper over a garbage alloy of recovered scrap that may contain copper.  They'll look like they're the right size but won't have anywhere near the current-carrying capacity, as well as breaking if you bend them too much when installing them.

Neighbour of mine was happy about the bargain he got on some cabling, until I pointed out what it was that he'd just finished installing...

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General Technical Chat / Re: Powering an LED from international line voltage

« Last post by NiHaoMike on Today at 01:15:30 pm »

That's possible, but to keep costs low, I'd like to stick to only one LED. Thanks for the idea though

Tiny SMD LEDs are dirt cheap. Design a small board with a whole lot of them on one side and some support components like a diode bridge on the other. (The main dropping resistor and/or capacitor remains external.) The tiny bit extra you spend on the LEDs is offset by the savings on the supporting circuit.

How about the classic NE-2 indicator lamp?

https://en.wikipedia.org/wiki/Neon_lamp

My experience with a NE2 and a modern LED in series (for a charge indicator on a high voltage capacitor module) is that the LED appears much brighter for the same current. The efficiency of those small neon bulbs is really low.

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Buy/Sell/Wanted / Re: Philips (Photonis) XX1080 50mm Image Intensifier with PSU

« Last post by COB on Today at 01:15:02 pm »

These night sights are best described here.

https://www.abex.co.uk/esales/optical/philips/image-intensifier/xx1080/xx1080_2/index.php

9

Test Equipment / Re: Siglent Bench DMMs SDM3065X, SDM3055 and SDM3045X

« Last post by Kleinstein on Today at 01:14:19 pm »

The jumps of a LM399 ref. are usually on the order of 3-4 µV or 0.5 ppm. So 15 µV would be about 3 times to large for the LM399 typical jumps.

With 2 meters in parallel, there is the possibilty that one meter sees the disturband from AZ switching of the other meter.  It may be worth checking if the problem also exists without the 2nd meter.

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Microcontrollers / Re: It Came from Mainland China: Bootleg MCS-251 "32-Bit 8051"

« Last post by DavidAlfa on Today at 01:11:44 pm »

No thanks, such a prehistoric architecture!
Poor docs, barely any compilers or toolchains...
Give me a much better documented and efficient arm or riscv mcu!