The saga of the doorbell

When we got our house way back in the last millennium it had a fairly good doorbell consisting of two tubular bells, one of which was about 18 inches long. This sounded all over the house but eventually the solenoid last its sparkle and the doorbell went from ding-dong, to dong, to a little tinny ding. So we went through a couple or three battery powered bells which were pretty pathetic and ate batteries. Eventually we settled on a wireless type from eBay and this worked well, and had two plug-in mains operated bells. But the doorbell push itself, sat out in the Yorkshire wilderness that is our drive eventually failed. A new set of radio doorbells was acquired from eBay, and this time the range was a lot better reaching all the way to the workshop. Slowly the range decreased and recently the outside bell push has had issues relating to condensation. No matter what I tried I ended up having to take it apart, clean the battery and put it back in time for the parcel person. Then then tags that held it together decided to go away on holiday and never return.

The original doorbell way back when was AC driven, 6V or so from a bell transformer and it looked as if it had been in for many decades. So, given that these new fangled units are either too weak to be of any audible use or fail regularly or both I made up a little box with an 8V transformer and wired this to an actual bells, not a ding-dong. The bell push outside is now just a switch. Being AC it will probably fair better but I have a space switch just in case.

So how is this radio related? Well, first off I have a relay wired across the bell as I plan to connect this to our Homebridge Pi to generate doorbell alarms on our iPhones. Given this relay I took the previous wireless bell push apart, unsoldered the push and wired this to a n/o contact.

So now the doorbell rings the bell and also triggers the radio bells. There, a radio project! Well, ok, it was only unsoldering a switch…

Portsdown / Langstone progress

Slowly coming together. Yesterday I decided to attack the front panel with a drill and mount the rotary encoder, switches and the little Arduino board which I programmed earlier. This is for tuning the Langstone. For some reason my drill press insists on making triangular holes – if I wanted a triangular hole I’d never manage of course. So I’ve resorted to making a smaller hole and using a round file. Anyway, everything went into place, although the Arduino board has no mounting holes so I’ve tie-wrapped a piece of plastic under it as an insulator and used a decent (hopefully!) sticky pad to secure the board inside the front panel.

So far, so good. Here it is receiving the Allstar microHub…

I need to sort the microphone out. The USB audio dongles seem to be constructed for stereo input so I wired the same to the front panel. Plugging the headset in gives no audio, presumably its all shorting out. I can make it work by ‘adjusting’ the plug (pulling it out until it works!) so I need to re-wire or make a little adapter.

There are a couple of fans in the case and so far it seems to be keeping nice and cool. Next steps include making the GPIO breakout board and possibly the band switching stuff.

Edit: of course I have a mono to stereo adapter plug, I just never looked in the junk box! Mic input now working fine…

Spectrum analysers

I’ve been looking for some time for an affordable (i.e. used) and useful ranged (i.e. not cheap!) spectrum analyser. Obviously I want DC to light but don’t need it and don’t want to sell the house for a bit of test gear. I have a TinySA which is good to 960MHz but I will need a higher frequency range as I fiddle more with microwaves.

The ultimate, e.g. a Rigol or Siglent LCD type device is just far too expensive. Nice to have yes but something one would need to be using all the time in order to justify it. Then I came across Satsagen –

Satsagen runs under Windows and by default uses an Adalm Pluto as its interface to the real world. The software even does the necessary to upgrade the Pluto to the ‘full’ range of 70MHz to 6GHz (you can do this easily by hand but it’s nice of the software to do it anyway). The software has three basic function too – spectrum analyser, spectrum analyser with tracking, and generator. So, one PC, one Pluto, Satsagen and you get a pretty decent 70MHz to 6GHz spectrum analyser, tracking generator and signal generator.

I have not yet delved into all the functionality and only carried out a couple of quick tests on a handheld and on my 70MHz transverter, plus a very quick test of a FPV transmitter (TS832) up at 5.6GHz.

It will work with other devices such as the HackRF and the RTL dongle but it seems so useful I purchased a Pluto just for it (yeah, ok, I can use it for other stuff too but hey)

PiBox progress…

The PiBox is almost completed. It’s taken far too long due to all sorts of silly things like having to get fans because a dry run indicated the poor little boards were getting a bit hot, having to get bolts for the fans because I had none long enough, and having to get a connector for the 1-wire (actually 3 wires!) lead from the central heating sensors.

So, there is is. Two fans on the left, 5V PSU bottom right, gigabit Ethernet switch above that, then the Pi’s: top is the PiStar with the DVMega board which has coax to the rear panel and then a dummy load, middle is the ASD-B and central heating monitor Pi, and the bottom is a general purpose one with various bits on such as rtl_tcp. The lower two boards have USB-A sockets on the rear of the case for the two SDR sticks, one for the ADS-B antenna and one to attach to a Discone for general use.

But there is an issue. I had originally intended this to sit in the shack but those fans are just too annoying. Not loud, but constant. I suspect the box will end up in the loft. Or maybe a re-think. I may fiddle with running the fans from one (or two) of the Pi’s and set up some temperature control to turn them on and off. It may even be that I am rather too ‘sensitive’ to the temperature range as others seem happy running their boards a lot hotter than I do mine.



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