Snap Circuitry PICAXE Micros

Introduction: Snap Circuitry PICAXE Micros

About: Retired educator/writer

PICAXE "snap connector" kids/seniors DIY microcontroller kit!

NOTE: This snap approach Instructable was initially rustled up ~2007, but with rapid e-progress I considered it dated & thus deleted about 2013. However, as both snap circuitry & PICAXEs have pleasingly remained popular (& cheap),it seemed worthy of dusting off for the next generation! Excuse lower res. pix from cameras of that era.

Be aware that this Instructable assumes a fair degree of knowledge about PICAXE-08M 8 bit microcontrollers. Refer to resource links if new to these nifty & cheap "BASIC speaking" micros.

Stan. ("Manuka") - Aug.2021

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Here's an nifty approach that fits a UK sourced PICAXE-08M micro-controller into the gutted sound module from a colourful "snap connector" electronic kit. It's designed around the simplest (& cheapest!) 80 experiment kit,but larger versions could be also used.

Popular & CHEAP high level UK sourced PICAXE micros are widely considered GREAT value educational & hobbiest micros, but impatient youngsters & fuzzy eyed seniors may find PCB soldering &/or breadboard circuit assembly too fiddly.

The approach taken here allows full PICAXE programming (~80 lines of high level PBASIC code), although only 4 of the normal 5 I/Os are initially available - quite enough for intro work! Sounds,LED flashing,sensor reading,timers,data loggers,simple reaction games, code sending, traffic light simulations, touch sensors etc- even 2 wire serial data comms to other units/PCs are possible. Basic electrical circuits included with the snap kits themselves of course can still be used.

Step 1: Background

These "snap connector" kits are globally sold under a variety of names, but here in New Zealand they're known as "Electronic Brain Boxes", with the simplest "80 Experiments" offering only ~US$15. Pre-teen kids thrive on them,& classroom management is easy, since no tools are needed. That's right teachers- NO TOOLS NEEDED!

I've used a swag of 30 kits as part of my educational "mad scientist" work, & had ~100s of hormonal kids tinker with them in the past 18 months. Amazingly however most are still intact & almost NONE OF THE PARTS HAVE BEEN LOST. The design of the kits in fact cultivates compulsive tidying up-complete sets have been reboxed in as little as 3 minutes! Young kids (some even preschool) have absolutely LOVED them, & the confidence boosting gained from assembling CIRCUITS THAT WORK is immense.

Note: It's well worth INTIALLY using a simulator to alert users to basic "lamp/switch/battery/connector" circuit components & layouts. Rather than subjecting the snap circuitry to smoking batteries & blown fuses the likes of short circuits are better first experienced on a simulator such as the esteemed "Crocodile Clips". Free versions are available via Yenka => https://www.mentis.co.nz/yenka-technology-software

Step 2: Engaging !

"Friday afternoon on a hot day", but note the ~25 engaged pre-teen kids! Issuing & repacking takes just minutes, & even the simplest "80" kit keeps a class focused for ~45 minutes. Working in pairs is often the best approach.

Step 3: Confidence Boosting!

How about this for pre school enthusiasm- kids don't even have to be able to read,as the colourful instructions are very graphical. And "Girls can do anything" too - hands on electrical fun has often been considered "boy's stuff".

Step 4: Fun- But What Next?!

Even the larger versions may however only provide a few hours of fun "as is" for most kids,& an enhanced challenge is really needed to stimulate curiosity. Teachers & parents COULD of course make up their own experiments & task worksheets - Ohms Law,series/parallel loads & switches etc. The larger & costly kits even have radio & metering options,suitable for mid level secondary school etc,& add ons are available.

However users keen to get experience with microcontrollers may otherwise have to work with solderless breadboards using fiddly circuitry,small components & intricate wiring.

Step 5: "PICAXE" That Noisy Sound Module!

But here's a low cost,& end user orientated, approach instead. Although the basic circuits are highly educational,both kids & (ESPECIALLY!) adults may soon tire of siren & machine gun noises from the kit's sound module. Hence, consider removing this C.O.B. (Chip On Board) device from it's "snap" housing & replacing it with a far more versatile PICAXE-08M micro instead!

An alternative would be to make your own PICAXE add-on,but it wouldn't look as professional,& suitable snap connectors have also been elusive here in NZ. US firm Elenco in fact offer programmable "snap" kits,but at a heady ~US$$($). These tend costly for what they are, & shipping costs may be daunting...

Step 6: Replacement PICAXE "engine"

Here's the PICAXEd conversion parts laid out ready to fit & finally fit nto the gutted holder. If quite a few of these conversions are being done, then set up a simple spacing template to streamline assembly & wire lengths etc.The space revealed here however is rather too tight for neat PICAXE insertion & soldering & can be enlarged significantly..

Step 7: Dremel Attack

A Dremel readily & neatly exposes right back to the solder tag contacts- existing wires are rather too flimsy & a full trapazoidal cutout gives best rewiring access. Use electronic colour coded wires (Brown=1, Red=2, Yellow=4 etc) to ID the connections,& DIP 8 socket the PICAXE- using a Veroboard offcut for mounting. Note the PICAXE I/O "PIN" channels are NOT the same as the usual IC legs, & an unusual supply pinout also exists (IC leg 1 is +ve,8 is ground)

Step 8: Ground Connection

Rather than waste a module stud for a ground connection a small bolt can be fitted in the module side wall. Use a hot air gun to bend a 2 contact strip to ~right angles so the snap socket nicely fits the bolt's protruding shaft. This makes for a convincing power supply GND & the freed up module stud can then be wired as a valuable PICAXE PIN0 output.

Step 9: Finished !

FINISHED. The top pix shows an initial trial layout with resistors soldered to the programming socket - the lower Vero board approach is much prefered! Yes-agreed-this retrofitting modification is a tad fiddly,but the wiring is not really critical. The small piece of Vero board makes for the neatest assembly,although a "rats nest" ugly layout can be used OK. Aside from the 5 links to the gutted module's connectors, 2 resistors & a 3.5mm 3 terminal socket are also fitted to allow programming via the PICAXE editor. Note the short link run to a drilled side hole connecting to the small bolt used as a ground connection via it's protruding shaft.

Step 10: Ready for Use

Ready for use & in fact wired as a nifty reaction time tester! Programming,using the usual PICAXE 3 wire serial lead connected to an editing PC,can be readily done via the 3 terminal socket. Extra circuitry (LEDs, 10k pullups etc) can be made simply made by modifying 2 section "snap" strips.The speaker should strictly have a 10 microFarad electrolytic & resistor fitted too. Extra LEDs will need a dropping resistor (~330 Ohms).

The PICAXE-08M itself runs on a supply from 3-5.5V,& use of a dummy cell allows either 3 x fresh AA cells, or 4 x 1.2 V NiCd/NiMH to be initially used. When they're weary,the dummy can be replaced with another near flat AA! Squeezing a few more useful Joules out of the batteries is environmentally (& tight budget) friendly.

Step 11: Power Strip

An amplifying action NPN Darlington based "power strip" can be made from a 3 connection strip. The action is easy to understand as it is similar to a car accelerator controlling the powerful engine.

Step 12: Higher Current Day/Night Lamp Control ?

Here's a current hungry filament lamp being driven under LDR (Light Dependent Resistor) program control via the DIY power strip. PICAXEs can only source ~20mA & are normally limited to driving low demand LEDs. The LDR (rescued from a larger kit) is in a voltage divider network with a 10k resistor & has it's resistance monitored by a PICAXE command.

Step 13: IR Control ?

Pin 3 (input only on a PICAXE-08M) remains unused, but scope for IR data reception exists for those with nimble fingers. These handy VISHAY 3 terminal 38Hz TV IR sensor devices need just +ve supply, ground & Pin3 data connections (plus a pullup resistor from the data pin to +ve). The PICAXE manuals offer extensive insights into their connection and use- enhanced IR handling is included in the PICAXE-08M command set.

Step 14: Traffic Light Action ?

This was suprisingly easy to layout & code. Tweaking tempts for different wait times & "what if" actions.

Step 15: Stepper Motor Insight !

Although stepper motors are increasingly used in the likes of battery power tools,their action can be difficult to investigate. This very low power bipolar type (sourced from Electronic Goldmine) draws only ~20mA from a 3V supply & hence can be directly driven from a PICAXE. If IR control was also used then all manner of motor sequences could be organised.

Step 16: SMT Hellschreiber

Audio tone sending via Sequential Multi Tone Hellschreiber (= "bright writing") is fun to investigate. "Hell" messages (which here are slowly "painted" onto a spectrum analyser app ) are reknowned for being still readable in spite of interference.

Step 17: Kiwi Kids at "work" !

End results- here are diverse 2008 era groups of Kiwi kids ( 7-11 yo.) exploring ideas with PICAXEd snap kits. The old Toshiba W98 serial laptops used for editing were quite suitable for such cost effective insights. Somewhat predictably flashing LEDs, sounds and simple games catch youthful attention - the reaction timer is particularly popular with competitive boys!

The real benefit of the modified kits at this level relates to mind extending investigations that can be carried out. Typical has been a night light "with attitude",controlled by an IR remote. Basic day/night PICAXE managed circuitry can be organised via READADC and a voltage divided LDR of course. Simple security setups that alarm only after PICAXE produced delays (rather than immediately) make for a clever way to catch rascals too!

Parts not issued with the kits can usually be organised with spare 2 & 3 snap strips, witness the DIY transistor "power strip" & 10k "pull up" resistor. Other sensors (thermistors especially) can be mounted in a like manner, and even a PV cell ( rescued from a solar garden lamp) may appeal.

Although the IR feature allows all manner of "wireless " links, a tempting extra is a simple (433 MHz ?) radio transmitter for sounds & audio coded data to be sent to a nearby receiver.. The likes of a simple "Swan Code", with tens = long & units =short (hence long,short,short,short =13) can suit for numeric data. Audio sequences, like the Sequential Multi-Tone (SM-T) Hellschreiber being sent across a room as "twinkling audio", are very appealing. Despite it's obsolesence, I've found even classic Morse Code still intrigues many preteens in fact. PICAXE Morse generation is pretty straight forward, and being able to recognise SOS ( .../---/... ) may one day save a life !

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Stan. SWAN => stan.swan@gmail.com <= Wellington, New Zealand. (ZL2APS -since 1967).

Step 18: RESOURCES

1. UK firm Revolution Education - the PICAXE originators ~2002 => www.picaxe.com

2. Extremely helpful (& friendly!) PICAXE forum => www.picaxeforum.co.uk

3. US "snap" firm Elenco => www.elenco.com/


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