Catch 22

[Lee Burke]

I was considering installing one of those Lost Model beepers, but understand it will not work as long as I have the Fail Safe option activated.  It doesn't sound like a good idea to turn that off.  What do think?

[Tim Mackey]

In my experience, lost models are often due to crashes where the battery often comes disconnected as well, and it wont work in that case either.

[Lee Burke]

I guess that's so, Timbo.  Thanks for your input.  It seems a shame not use the technology.  There is a lot of rough ground near me, if i go down there it might be a future archaeologist who finds the machine.  Good to leave something for the coming generations, I know ,but stll.

[iawnski]

 i bought one of them put it in my workshop (lost it)

[Lee Burke]

Good one , Lawnski

 I just found a beeper that can be used with the fail-safe option http://wingedshadow.com/rcrprod.html 

Of course, as Timbo says, if the battery has become disconected then you need sniffer dogs anyway. 

[Tim Mackey]

From a quick glance - this looks a decent bit of kit.

[Mike Hawkins]

You could make one yourself with a soldering iron and a few other electronic parts, it would be cheap and small, could have lost plane locater that works with PCM, voltage sensor and min voltage, also a small battery that supplies power only when disconnected from receiver. If youre interested and don't know where to go, let me know and I would be glad to help.

[Lee Burke]

Thanks Mike, that sounds great.   

[Johnnie]

Mike

I would be interested to build one myself.

[Bob Cotsford]

sounds like an idea for a magazine article - time was when RCME lived up to the electronics part of it's title

[iawnski]

jetsome  what happens if you got no teeth

[Ultymate]

It just "gums" back on it's own

[Tim Mackey]

Oh thats terrible Mr C !

[Mike Hawkins]

 G'Day Lee

 Thought I might start with a short intro about myself and a bit of a whinge.

 I am from Wagga Wagga, NSW, Australia. I am 17, still at school and love scale models especially the super accurate military ones built from plans. Now for the whinge, not only do you guys over in the UK have the awesome museums such as Duxford and the Shuttleworth collection but you also have the ideal electronic gadget to solve this and many other modelling problems.

 It's called a PICAXE. Their website is at www.picaxe.co.uk and the chips are as cheap as chips only about £1.50 each for an 08-M. They are microcontrollers which have been pre-loaded with code so that pretty much any one can use them. All you will need to program them is a few resistors a 9 pin serial connector and the the programming editor from http://www.rev-ed.co.uk/picaxe/software.htm. This is opposed to the £50+ to make the programmer for the raw chips aswell as having to learn a complex computer language.

The chips can be used to make anything from a switch (to replace servos and micro-switches), servo slower/reverser/delay (With a scale WWII model, if it has mechanical retracts with a servo each main, you flick the switch the right leg starts coming up a five seconds later the left starts and twelve seconds after you flicked the switch the gear is up), or an air pressure sensor so that when the retract air pressure starts to get low down goes the gear. It's limited to your imagination, well amlost.

Sorry, I don't have any chips at the moment to test the circuit as I design it, but I will post my ideas as I go so everyone can help me to design it to have what they want (hopefully I will have some in a few weeks). So in the meantime tell me what you want it to have and perhaps get some chips and start experimenting. Sorry this post was a bit long.

 Mike

[Mike Hawkins]

My ideas.

For the lost model sensor the PICAXE-08M should provide what we need along with a piezo transducer (it makes the sound) we get about 90dB. The back up battery will be regulated and have a diode so that it only supplies power when the reciever is disconnected, even then if the backup is a 12V battery only 10mA will be drawn. Some resistors will be used so the PICAXE can sense the Rx battery voltage (with the ideas I have at the moment it may not be able to read a voltage below 3.4V, however the chip and the receiver shutdown at 3V).

The program on the chip will read the voltage then count the number of pulses the reciever sends out in .65535sec. If this number is okay it will start again and read the voltage. If it is not it will check the length of the pulses, the length is okay it will go to the start, no pulse - make noise, pulses are same for 5sec - it's in failsafe - make noise,pulses are sparodic - make noise. As well as this if a button is pressed it will tell you the current voltage as well as the lowest voltage since it was turned on. The noise can be whatever you want from a hum to God Save The Queen (as long as there is room on the chip.)

Hopefully soon I will have a schematic to show how most of it will work, in the meantime if anyone wants to know about the BASIC language the chips use or the circuit, let me know.

 Mike

[Lee Burke]

Interesting stuff, Mike.  Say Hi to Wagga Wagga for me, never been there but I knew a young tennis proffessional from there back in the seventies.  Yup, you are right to envy us Duxford and The Shuttleworth collection.  This last should be the focus of a pilgrimage by any aviation enthusiast.  The Duxford show and its museum are not to be sneezed either, as you pointed out.  As to envying Britain its pica chips thats another thing altogether.

The info on putting together Lost Model Finder will be read with interst by many, I expect.  I look forward to seeing the schematic to discover if I can figure it out

[Former Member]

[This posting has been removed]

[Tim Mackey]

I already have done that one Eric - see the DX7 mods thread - it is just set for a different voltage alert - its based on the "microscream" weighs a few grams and involves NO PIC programming or knowledge at all.

Heres a link jimsky

[Mike Hawkins]

Hey all, here is what I've got so far. Im still waiting for some chips to test it, but as you can see it's fairly simple.

Connect either of the power parts to the control circuit. If using power I connect C to A. Here is a brief explanation on how it works. D1 and D2 make it so that the chip has power from the RX or backup battery, whichever has a higher voltage (if they are the same it comes from both - these also drop the voltage by about .15V). D3 and D4 do the same but as we have a 12V source we may as well use it for the piezo to make it louder. R1, R2, C1, C2, C3, D5, D6 and LM317L are to regulate the 12V down to 3.75V which you could do with a zener diode but the LM317L is more stable. R3 and D7 make sure the voltage does not exceed 5.1V and is equal to supply when supply less than 3.2V (The picaxe works from 3.0V to 5.5V). R4 reduces current on signal input, R5 and R6 are part of the picaxe setup to make sure it works properly, R7 and T1 turn on the piezo when pin 5 goes high. (My piezo only draws 3mA @ 12V - I tested it lots of times - this is amazing, the BC548 is easily capable of driving it. You may need to change R7 depending on how much the piezo you use draws.) R3 may also need to be changed depending on how much the circuit draws. Now all I need to do is work out the code to program on the chip and make sure the circuit works.

Mike

[Lee Burke]

Hey Mike, that looks good.  Doesn't look beyond even my ham-fisted abilities, though it could well be.  Just got to find somewhere to get the componants.  Now where was that Google button again?

[Former Member]

[This posting has been removed]

[Tim Mackey]

I will ask the boss

[Richard Hansford]

Have a look at the Loc8tor.  A small unit on goes onto the model and you can then find your model using the hand held direction meter.   The battery in the model's unit should last at least six months so you will have plenty of search time!

[David Ashby - Moderator]

Ok guys I can start a new forum folder ...what do you think .......electronics/gadgets and simulators?

[Tim Mackey]

DIY Electronics+Gadgets+Flight Sims