Sunday Afternoon Hacking

hippy

Technical Support
Staff member
#1
Courtesy of my local 'everything for a pound shop', Poundland, but I'm sure the hack can be had elsewhere.

They have some some nice looking "Battery Backup Packs" ( ">iPD2" ); about the size of a box of Swan Vesta matches ( pager sized ), 4 x AAA, on-off switch, a small power socket ( which a provided USB socket or other cable plugs into ), slide-off cover for the batteries and a top section which holds the PCB for switch and socket. It's got a pre-moulded pocket/belt clip on its rear.

Converting to 2 or 3 x AAA is easy, as is cutting down the switch PCB. Insert a panel mount 3.5mm jack in the hole where the power socket went ( or fly a cable out of it ), add a dead-bug wired PICAXE with the download circuit ( in the space at the top, or where the removed battery were ), and you've got an instant 'go anywhere PICAXE demo platform'.

Ideal for software testing with results back via SERTXD, and adding LED's etc shouldn't be much harder - all praise the inventor of hot glue !

Might even make for a nice personal temperature data-logger.

Find an emergency charger which has a USB socket, and you should be able to convert that to run straight from a PC's USB cable, no batteries required - you'll still need a serial download cable unless you fit a USB-to-serial inside.

With the model I got, with the power socket removed that can be added to any PICAXE board and the USB plug-in used to deliver power from USB.

And finally ... The end result looks a lot better than an Altoids tin :)
 

xstamp

Senior Member
#2
On a similar note, I recently purchased a wireless doorbell set for under £10 (from HomeBase) that has eight selectable operating channels and claims a range of 75 metres. I have already had the lid of the well made transmitter and receiver modules and found that the button input seems to have a weak pull-up to the transmitters 3V battery supply, and can be activated directly from a CMOS gate or open collector transistor. This information is only of academic interest as there is probably not a legal PICAXE application for this type of radio link.

 

manuka

Senior Member
#3
Hippy-good find. Reminds me of assorted "sprinkle jar"/35mm film cannisters approaches I've tried. Show off circuits often benefit from a clear case as well, suiting wide mouth (~20-25mm) tablet containers.

As small cases = small battery capacity ( c.p) one always has to factor in the supply voltage & cell sizes. Hence perhaps a more viable hack is to use the nifty 3 x AA switched battery boxes & bypass one of the cell bays. The then 3V Picaxe circuit can then be built into the removed cell position & still be switched after simple wiring adjustments. I'm wary of AAA designs as their energy content is pretty low for what they are, & AAAs also are quite costly compared with normal AAs.

Xstamp- as much as that! A similar Arlec design sells here in Aus/NZ for ~£5! The 8 "channels" relate to code preambles, as the unit uses just a single 433.92 MHz frequency. They certainly look worth Picaxing, & are quite legal. I recall the Arlec here has a very attractive receiver battery life,as it drops to a snooze mode between bell pushes & draws <1mA. Stan



Edited by - manuka on 12/08/2007 20:35:24
 

hippy

Technical Support
Staff member
#4
manuka : It was your 35mm can designs which inspired me to buy, with the added bonus of at least some type of battery holder built in. I agree with your point about AAA's being lower capacity.

I'm tempted to fit an 08M and an I2C Eeprom so it can spool out loads of text and fake being a belt-worn Linux box when connected to a terminal emulator :)

xstamp : I'd assume, unless anyone knows to the contrary, that if the band were legal/licensed to work as a doorbell it would be legal/licensed when working as a 'PICAXE pushed doorbell'. If you can identify its frequency, OfCom documents should clarify if licence exempt etc. It would be interesting to see if you can pickup the incoming signal at the bell end ( <i>ooer missus ! </i> ) what baud rates you could get out of it. The old diode pointing at a PICAXE pin could give you quick 'open-collector' output for serial.
 
#5
Re sprinkle jar/35mm film canisters as project cases, I have also used urine specimen containers. Unused, of course! I haven't yet managed to get a project into a blood specimen container but I am sure it is possible.
 

manuka

Senior Member
#6
Yikes- I've a near endless supply of these myself (medical family),but have visions of youngsters fossicking thru' needle spiked garbage bags looking for them to reuse. Hence IMHO these spec. containers are best left to their intended purpose,&amp; I'll NOT use or recommend them in applications outside their intended medical field. Stan
 
#7
I suppose it depends on the function of the device. I've used jiffy boxes screwed to walls, 19inch rack cases, and for out in the field, 90mm downpipe with a cap at the top sitting on top of a metal post. Many of the boxes are reused from other projects, as are many components including an endless source of wirewrap wire from the backplane of an old PDP10 <A href='http://en.wikipedia.org/wiki/PDP-10' Target=_Blank>External Web Link</a> (scroll down a bit for the picture).


Edited by - Dr_Acula on 13/08/2007 15:15:45
 

xstamp

Senior Member
#8
Hippy, have not yet tried to determine the data transmission rate of the door bell radio link but have made it into a wireless rain detector. When a stripboard &#8216;sensor&#8217; first gets wet it triggers a monostable to power-up the push-button module, which then transmits a single &#8216;rain alarm&#8217; pulse to activate the bell module. Very low power circuitry was implemented using a 4093 quad 2-input Schmitt NAND gate chip (sorry, no PICAXE).

 
#9
further to Manuka's comment on the specimen containers, they aren't all that greater container as the plastic they tend to be made of is usaully errin on the very brittle side and even small drops of 1/2 a metre can proove fatal and in some cases messy,

some of the more indestructable cases i have used in the past are those galvanised threaded pip fitting availble at the hardware store a simple 1 or 2 inch pipe section with two end caps , to make them look better stick them in a lathe and you can clean up the surface,making what can look like quite a nice and clean case not to mention indestructable ..... especially if you use expandafoam to suspend your pcb and rechargable batteries in place
 
#10
xstamp &quot;....as there is probably not a legal PICAXE application for this type of radio link.&quot;
I have used wireless doorbells in add on to picaxe project as short range wireless pagers. How is this not legal? It seemed a good idea at the time.
 
#11
sorry, should have read hippys post. My project did involve having the receiver in a vehicle &amp; was set off when driving through a rural city. (A nearby wireless doorbell)
 

boriz

Senior Member
#12
My favourite enclosure hack is also from a local pound shop. It&#8217;s supposed to be stereo extension speakers for a personal music player. For &#163;1, you get two enclosures, each with a nifty front grille and 8 ohm 0.5w speaker (easily removable) and a stereo plug and lead. And they are a very convenient size.

Pictures:

<A href='http://www.zen86415.zen.co.uk/P8150510%20(Medium).JPG' Target=_Blank>External Web Link</a>

<A href='http://www.zen86415.zen.co.uk/P8150511%20(Medium).JPG' Target=_Blank>External Web Link</a>

<A href='http://www.zen86415.zen.co.uk/P8150514%20(Medium).JPG' Target=_Blank>External Web Link</a>
 

xstamp

Senior Member
#13
rolsen,

Using wireless doorbell modules to send data may well be legal, but I can see two potential issues:

Once the module is opened and hacked it may no longer be &#8216;type approved&#8217;.

Even though the equipment is transmitting on a licence exempt radio frequency, its use may not be legal.

If you take a look at the Ofcom document &#8220;UK Radio Interface Requirement 2030 Short Range Devices&#8221; you will see what I mean!




 
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