Recent Posts

1

General Technical Chat / Re: STC-1000 thermostat retrofit to fridge freezer

« Last post by sparx on Today at 02:07:15 pm »

STC-1000 fitted and working!

There is a bundle of cables from the compressor electronics box to up inside the fridge/freezer inside a rubber sleeve. I opened the sleeve (and the electronics box) to figure out which wire was which. There were spare spade terminals for every connection except the incoming live... So I had to join mid-way up the cable to the original thermostat. I used some Wago terminals which were on hand, I'll check how they're holding up in a short while as they're near the compressor.

I obtained a 12V version of the STC-1000 after deciding that I would use a higher current rated relay to switch the compressor on, so the STC-1000 switches 12V to a relay that sits in the base of the fridge freezer.

The thermistor location is still being worked out, although taped about 3 inches below the door switch seems to keep the fridge at a nice well controlled 1-3 degrees, and freezer at -20 to -24.... so result! Also has the nice added benefit that if the door remains open because you're putting stuff in from the supermarket, it kicks back on and starts cooling immediately, and the daily power usage has now returned to it's rated power of 1.44kW.

I thought I took pictures, but unless my phone has lost them, I might have been too far into the project to remember!

2

RF, Microwave, Ham Radio / Re: Using spectrum analyzer to debug NRF24 module

« Last post by MarkF on Today at 02:04:25 pm »

Have you seen this thread?
https://www.eevblog.com/forum/projects/setting-up-the-nrf24l01-for-transmitting-and-receiving/

Show us your hardware and how the nRF24L01 is connected.

Are you using the nRF24L01 or the nRF24L01+

I've found that a bulk capacitor of 1uF near the nRF24L01+ is necessary.

Also, checkout the nRF24 library for Arduino.
Even if you're not using an Arduino, the code is the same.
Forget about hardware debugging.  It's not going to help.

3

General Technical Chat / Re: JWST Takes a new photo of the horse head nebula

« Last post by Gyro on Today at 01:58:03 pm »

Stunning.

Shots like that make me forget about all the fuckwits in the world for just a short moment.

It also brings a sense of reality to how insignificant they, and the rest of us, are in the 'grand scheme'.

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Metrology / Re: Why don't we see more TDC based high-resolution ADCs?

« Last post by nimish on Today at 01:55:18 pm »

To spitball a TDC based DMM front end:

Exactly the same as a regular integrator but uses high speed comparators to trigger at, say, 0V and Vref/2 and then measure the time to integrate. You could easily linearize this and calibration could be done automatically I'd assume. PVT probably kills you but for a fixed temp, voltage and process -- n=1 -- I suppose you could do quite well.

5

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

« Last post by mikeselectricstuff on Today at 01:53:32 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.

There are also LEDs with multiple die in series in one package, mostly white for lighting applications.

6

Beginners / Re: 5V buck converter debugging

« Last post by __steven on Today at 01:52:39 pm »

I notice two things. One, Cboot/SW4 indicate a 50% duty cycle gate drive, however, we do not see the 0 to 3.7V pulse at 50% duty cycle that is expected at SW1/2/3.

The other is that indeed the input voltage rail is collapsing which likely leads to the IC turning on and off because of it's 3-4V under voltage lockout. What is your input current limit?

Can you confirm that the picture of SW1/2/3 is accurate? It looks identical to the "Vout (Vin=3.7V RMS)" picture. I recommend using one shot/single mode to remove the other waveforms from the screen. Easier to read that way.

I will say, assuming that the picture was indeed wrong, and you do see the 0-3.7V 50% duty cycle pulses at (SW1/2/3, pin 1 of L1), I think it is working fine. The output voltage is sitting at roughly half the input voltage which is what we expect with a 50% duty cycle. I cannot find information on the behavior when the input voltage is lower than the output voltage setpoint. With no load and no short, having an input voltage lower than the output target should not destroy the IC or cause an overcurrent condition.

If you believe it is safe to do so, I would suggest bringing the input voltage up and try and remove the undervoltage lockout from the behavior.

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

« Last post by mikeselectricstuff on Today at 01:52:29 pm »

If all you want is an indication that power is ON then NE-2 neon + resistor is difficult to beat in terms of simplicity and reliability.

Where do you get the surface-mount NE-2's from ?   

8

Projects, Designs, and Technical Stuff / Re: Brinking Light pattern for maximum attention distance at night

« Last post by NiHaoMike on Today at 01:47:36 pm »

Although an SOS is probably easy to recognize, I don't think that's a good idea unless there is an emergency.

There used to be a popular ringtone that's similar to SOS but with a crucial difference - only two long beeps instead of 3. So it's similar enough to catch attention but different enough to not be mistaken for an actual emergency call.

9

Test Equipment / Re: Vevor SDS1104 for first oscilloscope?

« Last post by BrokenYugo on Today at 01:44:40 pm »

I would normally agree but also anticipate some of the current Siglent SDS1104XE owners upgrading to the newer SDS800 series which should inturn increase the number of earlier scopes available in the second hand market.

If the price is right then a used SDS1104XE in good condition would still be worth serious consideration particularly for somebody on a budget. If the OP is not in a desperate rush for a scope then this would be my recommendation, cheaper than new and far superior to what they are currently considering.

I don't know what the market looks like in Australia, but I have been watching various sites here in the US in hopes of finding a deal on a used Siglent SDS1104XE or Rigol1054DZ. So far, the only things I'm finding are people offering them, used, for prices HIGHER than what I can get them brand new from Amazon.

Yeah, I don't think I've ever seen a late model lower end used DSO for sale that wasn't within $100 of a new one, not worth it IMO, especially on a common "beginner" model that's potentially seen who knows what ignorance induced abuse. And that's when you find them.

10

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

« Last post by soldar on Today at 01:41:29 pm »

If all you want is an indication that power is ON then NE-2 neon + resistor is difficult to beat in terms of simplicity and reliability. It is what is still used in switches and power strips. I have quite a few that are half a century old and working like the first day.