not what you think!

Thanks a bunch, and yes, I have thought a lot about it... like I said, I don't sleep at night, so that's about all I can do around here at night is think.

Well I already know Jameco, EGM, Digikey, and Mouser don't have most of the parts, but I'll try the rest.

Well, if you know of a replacement IC that can take the place of 4511B, please let me know, this seems to be the only part EGM is lacking, and they've got great prices.

also, could I use a regular 555 timer in place of the NE555, I know NE555 is a dual timer, but could a regular one be substituted ?

Some answers

Sorry for suggesting only UK suppliers but as I am in the UK and you never said where you are,
(you can type this into your profile if you wish - it does help others to relate to you)

4072 has been removed from the latest revision of this circuit anyway 8)
4511 - I'm not aware of a reasonable substitute :cry:
However neither appear to be 'discontinued' by the manufacturers so this must just be your supplier rationalising his stock :!:

NE555 is just a boring single timer, use an LM555 or SA555 or whatever ...
you could even use a 4093 quad Schmitt NAND configured as an oscillator - all you need is a clock pulse.

Ongoing Saga - Update

Just finishe scribbling the latest version of the circuit,
Everything works as we wanted but the reset pushbutton is less than perfect -
- sometimes presets to zero or random high value,
- should preset to value set on BCD switches
- I'm sure this is just a simple timing issue with the reset logic but no time to sort it just yet :?

For the circuit operation-
Counts down from any value set on BCD switches via the RESET pushbutton,
Counts in minutes and seconds (seconds resetting to 59 when it decrements minutes)
Freezes at zero count (detonate bomb)
Changes LED colour if disarmed before detonating
All the above features use the same lump of logic which is currently just 2 4093 quad Schmitt NANDs, a handfull of diodes and three transistors.

Mostly as in photographs posted above - too similar to be worth more piccys :wink:

Nice man, Thought of another trap, Heh, add my trembler unit to it, have that be the instant detonation, if you missed it basically how it works is if the trembler, or case is touched, or the case of the bomb is moved to hard, the wires make contact and BOOM!

Only you'd have to make the cut to detonate part in reverse.

You'd have to have it made into a "Close to detonate" circuit.

Dunno how you'd manage that one, just an idea, perhaps put that at the end of the bomb output, so if they do cut the wrong wire, it won't be apparent until the trembler is touched.

For the piccy, okay well ascii of the trembler see the Pendulum topic.

It would certainly make a change from the wobbly wire and buzzer often found at the village fete.

Here are a few thoughts for future designs:

Mount the whole lot in a clear perspex box with a hinged lid.
then use an ultrasonic or reflective infra red circuit to speed up timer when the lid is opened.Augment with recorded manical laughing and a further increase of speed if lid is then closed.
Metal and capacitive sensors can also be used to great effect, give the "contestant" a choice of tools to work with, arm and disarm different applications dependant on the type of tool detected.

Finally add a silly disarm circuit, that requires the use of an equipment item common to all the cadets.
Or if it is to be used at a fund raising event a coin operated switch must be activated to prevent a soaking.

You say that you want to use the circuit for training, one serious improvement I can suggest that the circuit itself randomly select a single wire to cut for disarm from a choice of paths in plain sight . This stops any , previous experiance shall we say , of being any use to the next attempt.

Have you considred electonic electronic dummy "land mines" ?

Ok, guys just a bit of eye-candy for you....

This is the timer circuit design. I've still got to make the PCB yet. I think it should work, but will be waiting for mechie to check it first, before I start building it. We're almost there with the rest of the design, just got a few bugs to iron out.


**broken link removed**

The Final Countdown ?

OK, try this ---

The circuit works a treat, I have varied the supply from 4.5v to 12v and it still works OK (the LEDs are dim at 4.5v but still readable).
Any valid time can be set on the BCD switches, from 1 second (!) to 99 minutes and 59 seconds.
You can set 79 seconds and it will work perfectly but is it sensible ?
Trying to set 80 or more seconds results in unpredictable start values, I have made no attempt to prevent this,
relying on common sense, the BCD rotary switch could be mechanically prevented from going too far ?

The circuit around the 555 timer can be exactly the same as the original zapwizard posting with the exception of the 'DISARM' wire,
which now also changes the display colour to green.

All wires that may be cut have some limited static protection in the pull-down resistors
which also maintain a known logic state when cut.

FAULTS FIXED-
Mainly the method of clocking the minutes counter from the 10-secs counter --
when the seconds got to zero (assuming there are minutes still to go) the logic reloaded the seconds counter with the value '59'
and relied on the carry out of the 10-secs counter to decrement the minutes.
This carry output was noisy during the load operation and caused random operation of the mins section - racing?
By using the Q4 output (count is greater than decimal 7) the problem is avoided.
Other bits of logic are tidied up and a few unneccesary components deleted.
Typo error - I had the NAND gates labelled as 4091 - :roll: now correctly shown as 4093.

Whoa... Complexity...

Whoa... Complexity...

Click to expand...

It's not that bad! Especially when you've got someone who knows what they are doing!! :wink: (Cheers Mechie).

I've got the circuit re-drawn using Livewire. If anyone fancies taking a look at the Piccy. It's **broken link removed**. Be warned it's about 500Kb. I'm just waiting on for a cost of the PCB to be made up, and just clearing up a few little bits with Mechie and the building should start soon afterwards!

I managed to acquire an Ammo box.... Piccies below for those interested.

**broken link removed** **broken link removed**
**broken link removed**

Still waiting for PCB estimate, though.

Nice man, good luck...

Adding any of my trap ideas ? heh... or are you gonna wait for further models ?

Not for the minute. The project has already become far more complex then I had originally planned. Although I will see what I can do in later revisions.

The one advantage I do have over the original design is that I can just hot plug in any pyro device. Ie smoke bomb or flash bang etc.

What are the diodes

Hi,

I was working in a similar project to play a 'counter-strike like' game (paintguns and friends )

1. Could someone tell me D1-D17 are what kind of diode....Part number I mean
and Q1-Q2 too...could I use a 2N3904 ???

2. can I put 9V to 4093, 4029 and 4511 or I must power them with 5v ???

3. BCD switch are: right angle rotary BCD switch or 0-7 rotary switch

And I would like to put the timer to 35 secondes only, can you simplify the shematic to leave only 2 led-display

thanks

Part number for the rotary switch that I'm using from www.rswww.com 379-5177

The current circuit design will take 5V - 12V

If you only want a 2 digit display then I suggest that you look at the original design here and just use 2 instead of 4 displays. You could also hardwire the 35 seconds rather then use the rotary switches. But your best bet would be to wait for Mechie and see if he's got time to draw up a schematic. It shouldn't take him too long as the circuit isn't as complex.

transistors 2n3904 sounds ok to me. I'm using www.rswww.com part number 812-500 for the diodes.

will wait for Mechie

Thx craigey

Mechie, I will wait for a new shematic (no bcd - 2 digit only) if you have time for this.

Im gonna use 555 circuit for stopping detonation.
I dont want to cut a wire so I must press a switch 10 seconds OR another key-switch 5 seconds (like a defuse kit) to stop the 'Thing'

I already got the circuit (I think) for that and I will put togheter with the new one.

(Im using Circuit Maker 6 (Student version)...if you want to send me a shematic file)

thank u, cya

you could try something like this.
**broken link removed**

The circuit would be deactivated by turning 4 key switches. (the circuit above shows 4 Normally open key swtiches, but they should be normally closed). Anyway it's just to give you an idea.

Good luck

too easy ;-)

Thanks for the new plan
but 4 keyswitch seems to be too easy that is why Im gonna put a circuit with only 1 keyswitch but it must be use 10 seconds to desactivate the 'Thing'.
If you release the keyswitch before the 10 seconds down you must use it 10 seconds again.
But you can use another special keyswitch 5 seconds (similiar to a defusing kit) only to desactivate.

I will try it next week (money !! !!!)

ciao

It's been a while since I've actually designed anything remotely complex. I studied electronics at college about 4 years ago, but never had the oppurtunity to use what I had learnt. So know my knowledge is a little basic.

The diagram also uses set switches which will require you to push the first one 3 times and the second 5 times for the 35 seconds you require.

It sounds to me that you need a flipflop / latch circuit for the deactivation circuit.

Anyway hope it's of some use to you.