A little Saturday afternoon project last weekend was putting together this geiger counter kit from RH Electronics in Israel, paired with a soviet SBM-20 Geiger-Müller tube sourced from an eBay seller in the Ukraine. Total cost was £32 which seems very reasonable to me.
The RH Electronics kit comes with all the components apart from the Geiger-Müller tube, it is all through hole components (there are a few SMD components in the design but these are presoldered) and the PCB is well labelled so it is very easy to build. It runs on 4.5-5.5V, has a very low power consumption, stable HV output for the G-M tube and support for both 400V and 500V tubes. It also provides a handy interrupt output so that it can easily be linked to your favourite microcontroller.
The reason behind the last post was so that I could create a node for Node-RED to send pins to the Timeline on a Pebble smartwatch.
To use this you obviously need a Pebble Time (or a classic Pebble once the Timeline update is available) but you will also need a Timeline user token which is unique to you the user and an installed Pebble app. I detailed in the last post about how you can create a simple app to get a token or you can just install my Timeline Token app on your watch and get one that way.
The Timeline User Token is entered into the node and is stored in the credentials file in your .node-red directory.
Getting a token the easy way
If you just want to do it the easy way I’ve created a Timeline Token app which is available on the Pebble Appstore, once installed on your Pebble it will display the token and give you a short URL to view it on the web (to save retyping the lengthy UUID from the Pebble screen).
Another post I’ve been meaning to write for a long time. I finally got my Rigidbot 3D printer in August 2014 some 9 months later than the estimate but I was one of the lucky ones, many had to wait a lot longer and some have even had to pay extra for delivery, having already paid it once as the company completely ran out of funds. I am very happy with the printer though, I’ve printed all kinds of things since I’ve had it and it has produced some great results.
One of the main things I had in mind for it was printing customised enclosures for my electronics projects. I’ve used a variety of off the shelf cases for my indoor TinyTX and Tiny328 sensors, my favourite being the Evatron EN30W sensor case but I really wanted to design something of my own.
I mentioned in the last post that I send all but a select few callers on my landline straight to voicemail but that’s actually no longer true. Thanks to a casual comment by @ichilton on Twitter I’ve recently switched to diverting calls from unknown numbers to Lenny.
Lenny who? Lenny is an Asterisk dial plan which together with a set of very convincing recordings works as a bot to fool telesales callers into thinking they are talking to a real person. Lenny will answer then wait for the caller to speak and when they stop he moves on to the next recording, it really is very convincing and there are some great recordings of people having lengthy conversations with him on this YouTube channel.
I’ve used Asterisk at home since around 2004, originally using a clone of a Digium FXO card and later a Sipura SPA-3000 (later owned and branded by Linksys) to interface to my landline. When that server decommissioned itself (with a bang and bad smell) a year or so ago I switched over to the Asterisk based FreePBX on a Raspberry Pi (using the RasPBX distro) but still using the old but perfectly serviceable SPA-3000. It’s rare that anyone I want to speak to calls me on the landline these days (hi Mum!) but I need to keep it active for my BT Infinity fibre broadband so I may as well have something connected to it. Most of the calls I do get on it are junk so I have Asterisk set up to only ring the phones for a specific set of callers and anyone else just gets dumped straight to voicemail or rejected.
I had long used the unofficial Google speech API for voice notifications (TTS) as it has a very good, clear voice, much better than Festival which I had used previously. However late one night a couple of months ago this stopped working as Google started to redirect it to a captcha if you tried access it directly. That’s fair enough I suppose, it’s their service to do with what they like and it was never even advertised as a publicly available API for this purpose so all of us who were using it were on a free ride. I’m sure there will be ways around this but it got me looking at alternatives again.
This lead me to Ivona which is a speech synthesis system originally developed by a Polish company but is now owned by Amazon. Using their beta Speech Cloud service you can get a free account for “development purposes” which allows you to make 50,000 requests per month. I don’t know about you but that is more than enough for me.
This was a quick project to add notifications for when I get real physical mail. This is something I’ve had on my mind since I made my first SMS doorbell notification system back in 2004 and I finally got around to it last month.
First of all I picked up a cheap internal letterbox flap and fixed that over the internal side of the letterbox opening. Then I took a microswitch that I had salvaged out of an old dot matrix printer some time ago and made a little right angle bracket from some perforated metal strip I had lying around. A few little adjustments to the microswitch actuation lever and I had it operating the switch as soon as the flap was moved even only slightly. It also operates it as it closes but that is easily taken care of in code to prevent duplicate notifcations and can also be used to detect if something is stuck part way through the letterbox instead of being pushed all the way through.
I last blogged about this in December 2013 when the second version of my ATmega328 & DS18B20 based temperature sensor, installed on 29 December 2011, had just reached the 2 year mark on the original set of batteries. That’s pretty good going and I’d have been happy with that but how long would it last until those Energizer batteries needed replacing? Well I found out in March of this year when it finally started to report erroneous readings, yes that is over 3 years on one set of AA batteries. To be honest, I did have a false alarm a few weeks prior when it started to transmit very irregularly but it recovered from that, presumably due to the increase in temperature affecting the battery capacity.
This is a small dev board I designed to make experimenting with and deploying the ESP8266 ESP-03 modules a bit easier. As well as breaking out all the pins to 2.54mm headers it has a position to fit either a DS18B20 temperature sensor or a DHT22 temperature/humidity sensor plus the required pull up resistor. It can be powered from 3.3V or 5V+* if the regulator is fitted and there is a footprint for a micro USB connector if required.
*The regulator I used is good for up to 18V but I don’t know how far you would be able to push it with only the small area of PCB that is used as a heatsink. I would imagine it will be OK to at least 9V.
A 3 way pin header allows a jumper to be moved to switch between normal running mode and flash programming mode. With the jumper in the RUN position GPIO0 is connected to the header marked 0 and in the PRG position GPIO0 is grounded. It needs to be powered up with the jumper in the PRG position to enable programming mode.