#330 Lockdown Mailbag (Portable Power supplies, NRF52840, Strong servos, LED Signal, Ailunce DMR)

If you want to do AC power measurement, I'd get an Sonoff S31 smart switch (about $17 USD), and put Tasmota on it. You can then view the power measurement anywhere on a web page:


Voltage 122 V
Current 8.190 A
Power 1000 W
Apparent Power 1000 VA
Reactive Power 0 VAr
Power Factor 1.00
Energy Today 0.180 kWh
Energy Yesterday 0.474 kWh
Energy Total 3.417 kWh

Love this videos. Very interesting and useful

Can the usb power supplies with the usb a output also measure usb devices?

Please do a vid on the IoT Cricket. I have ordered two :)

As for the three lights - use it as a meal time warning:
Green - it's being served - time to stop what you are doing
Yellow - it's on the table - you have been warned
Red - it's in the dog!

The USB power supplies looks like a portable PSU if using a power bank with QC port enabled :P I'm also anxious to see the AC power . keep safe and heal quick

You need to power that servo separately, it's cutting out as your servo tester cannot provide adequate starting current for the motor, causing a brown out.

Do you know if that radio can be used to call the Rega? I had a hard time to find one and the one I got (Puxing) it’s also banned by the ofcom (I’ve an HB3 license)

Those servos are nice, useful that one can get very strong ones.
Definitely have to watch to not get fingers in the way of those when they move.
I also thought, that beacon would be a perfect traffic signal for the car garage to assist with parking.
On the subject of little boards with micros on them, we are spoilt for choices with cost effective devices these days.
It has two serious advantages for me, rapid prototyping and for low volumes just use one of these devices for the end product.
For low volumes it means I just buy something off the the shelf and use it, no point in laying out a board for something I need one or two a month of.
An arduino Uno and two line IIC lcd display costs so little, for low volumes I just use that in my solution, as an example.
Anyhow, my mind wandered.
Thanks for the chat.

Can't you talk to a guy in Tokyo using an ordinary phone? What am I missing?

Lots of interesting stuff here. Thanks for the video!
Where did you get the multimeter testleads with the small grippers at around 8min in the video?

Dear mister Spiess in Switzerland a high voltage device runs on over 1'000V so the power monitor runs on so called Niederspannung.
Like ur videos! Keep doing them...👍
To the servos, they tend to draw a lot of current, so u need suitable powering. (I would guess something like 10A peak)
Grüessli vo Rapperswil

Love it thanks!

an NRF52840 project would be very interesting! can it deep sleep using Arduino platform?

How is your finger doing?

Oh boy, a free cloud IoT service! I can't for my $20 purchase to become a brick because the operators can't be honest with themselves about how long they will want to spend their money to run a service for freeloaders.


No plans for long term support = no purchase

some women need a safe word.. maybe use the red, yellow, green light as a substitute for that??

like your gloves - useless - and just a suggestion get rid of that fucking weird hat and googles

Another idea for the red/yellow/green lights: a status light for your long range radio links (e.g. LoRa satellite)

Hi Andreas,
I miss the surprise of opening the packages, because it's part of your mailbag (with the Swiss knife) and half the pleasure as myself opening one...

We switched our everyday radios to HD1 handhelds and they have exceeded expectations. We use radios everyday, all day. If I wanted to play in DMR, I would get a BTech 6x2 or the Anytone ??? (same internals, different firmware). But, for good, solid work radios on the cheap, nothing beats the HD1, IMHO.

What was the USB-"volume knob" at the was not described ?? - Best 73 de oz9els

Did you by any chance get the idea for buying the LED tower after watching that Strange Parts video? :D

It's still very easy to get electronic components in the US, even components that I know come from China, Korea, or Mexico, but I don't expect that to last more than a few more months.

As if the world doesn’t have enough problems it’s beyond sad China churns out millions of fake products from fake harmful baby formula to fake transistors and ICs. If we could add up all the damage done by Chinese fake products it would be staggering. It’s a problem the all powerful Chinese government seems to mostly ignore just like they haven’t shut down live coronavirus carrying animals being sold at markets.

Wouldn't it be nice if these USB Power supplies could actually be controlled/monitored from USB?


Maybe s simple Serial interface to set Voltage and current limits and to read the current voltage/current. This would allow long time experiments monitoring energy usage, or capturing charging curves of batteries,...


Maxbe adding an arduino to turn the nobs could do the trick?

Andreas. As a mechanical engineer, I will be interested to see you talking about torque. The car companies sell cars based on power, but it is torque that really matters. The gearboxes in the servos are ‘mechanical torque amplifiers’ but the power of the motor is finite. Make sure you have an ammeter on the motor and all will be clear. I will be watching!

Check out the JX Servos. Full metal gear. Have build an automatic cable cutter with an JX HV7032MG.

Very enjoyable. Thanks for the video. It's appreciated.

what is wrong with the ESP32 BLE? :).... waiting for your findings on the nRF52840

I can't wait for the Cricket video :O

Good Video, as always. Thank you, Andreas! When I read „Portable power supplies“ in the description, I hoped you would show some kind of portable rechargeable power supplies using Li-Ion or lead-acid batteries... Take this as a suggestion for an upcoming video... As a long term subscriber of this channel and a fellow ham, I am very pleased to watch your videos on QO100 and other ham-radio-related things. Mixing in a bit more ham radio stuff has made the ‚electronics-cocktail‘ of your channel even tastier to me in the latest time!

Calling a servo "digital" is a little bit of marketing gimmick. Doesn't per se make the servo better or worse. A digital servo just has a microcontroller inside that measures the servo pulse length and controls the motor depending on that to match the internal potentiometer (on the output shaft) position to the signal. In analog servos that same thing is done with analog circuitry.

any possibility to talk about mechanical keyboard switches?

Have you noticed how the prices on Ebay has increased the last 2 months ? Free shipping is almost gone too from my old suppliers. Example the blue SDR-RTL receiver used to cost around £6-7. Now 9-10 + shipping + VAT ? Is the VAT sent to my Goverment in Norway or somewhere else? I have many examples.

Super! Pity you did not leave the CO2 meter running, we are dying to see the levels in your shack.

Got 2 Baofengs. They transmit just about anywhere. Going to get a DMR too, more and more of our local club get them.

Very interested in this nrf52 as a platform for battery operated sensors. As i understand well it has much lower deep sleep (and normal operation) power consumtion than esp32.

Looking forward to that NRF video, I've always liked the specs I've seen on their chips but never worked with them so depending on your experience with that one I might pick up a few.

What about arduino PORTENTA H7? Will you order it?

The stack lights are commonly used in factories for factory automation and to tell when the line is down. They are ubiquitous there. Looks like you managed to get your hands on one!

Very good products Professor Andreas. I'm so excited to see your video about NRF52840, as you said before, Nordic's chips are great promises at the market of microcontrollers. When will you make a video about the NRF51 or NRF52 family??!

When i see Thumbnail lockdown Malibog

Is it me or is the sound not correctly synced and lagging behind

Some interesting objects to play with. I would like to see a video on the NRF52 please. In particular how its power consumption compares to other microcontrollers for battery projects and also how to program it, possibly with the Arduino IDE?

An idea for the 'traffic lights' might be to fix it outside of your laboratory, to indicate red, when recording a video, or green when safe to enter. Orange for working (enter with caution) maybe.