Does anyone have schematics for building a beeper box (training hit box) for epée? I suspect that it is similar to a test box with added circuitry for holding a buzz and light for a pre-determined time.
basically all you want is to wire a 555 timing chip in monostable mode with a timed reset. Instructions for doing this may be found in divers places online. When I get my main comp back and repaired, I'll draw one up. I think someone else did once, tho.
The only way to atone for being occasionally a little over-dressed is by being always absolutely over-educated. -Oscar Wilde
I'll try to draw mine up ASAP, It may take me a day to get it up though. I have a box that will buzz for a little over a second, and it's just as telk described, a 555 in monostable.
In paragraph form, and forgive me if I oversimplify:
You want a 9V Battery, a Piezo Buzzer, a socket (or three banana jacks) a 555, a 1k to 100k resistor (value not impotant) for pull-up, a 0.1microfarad capacitor, and a resistor and capacitor for timing. Buzz time is approximately 1.1*(R*C). A power switch (SPST) is useful if you don't want to pull the battery out when you're done.
If you want to use a switch, wire it between the battery +9V and all your other Vcc connections.
Tie ground (battery Neg) to the 555 GND pin and either the A or B jack (either of the two closest pins, I'll use A) on your socket. The pull up resistor get's connected between the other jack and +9V. That jack (B) is also tied to the TRIGGER pin.
Connect the RESET pin to the Vcc pin, and tie them both to +9V. Connect the CV (Control Voltage) pin to Ground via the 0.1uF Cap (for stability).
Connect the THRESHOLD and DISCHARGE pins together, and tie the them to Vcc (+9V) via the timing resistor, and to Ground via the timing capacitor.
Connect your OUTPUT pin to the Piezo buzzer (Red wire if it has leads) and tie the other piezo lead to ground.
Here is a 555 tutorial I found, that could help those with less background in electronics see what the chip does and how it works in the previous description by Pepster.
Here's a Schematic, It may be a little confusing. I'm happy to clarify.
It may or may not attach right, we'll see if the board script likes me...
--- EDITED 5/20 at 4:30 EST ---
Sorry about the mix-up, The prevoius scematic was wrong. If you connect the RESET as shown, it is different than the description I posted earlier. The desription was correct, the correct schematic is attached.
The RESET is active-low (Reset the timer when the voltage drops to 0V) so tying it to Vcc disables the reset.
-Pep
Last edited by Pepster; 05-20-2004 at 05:33 PM.
Reason: Wrong Schematic
What exactly do you do to put this all together? I tried buying a little board thingy from Radioshack and soldering the components together.... I am crap at soldering.
Pepster, you say "Connect the RESET pin to the Vcc pin, and tie them both to +9V." If I am correct, that means you do not want to use the RESET function of the 555 Timer. However, in your posted schematic, you choose to RESET the timer with each depression of the épée tip. Which one do you have built?
In the schematic version, I think the RESET after each depression thingy would work if the delay time from reset trigger to Output was less than the delay from input trigger to Output. I hope that made sense. Also, what happens if you continually depress the tip? The Input should keep on re-triggering, but shouldn't the reset keep on re-triggering too?
Here's a tip: *don't* buy your ICs from radioshack. Rumor has it they sell factory reject parts, and after purchasing several not-working AND gates, I believe the rumors. Go to some other local electronic store. However, "Getting Started in Electronics by Forrest M. Mims III" is an excellent book, and is sold at ratshack for $5 or so.
And pepster, you should be able to solve that foil/epee problem with a cleverly placed transistor.
The only way to atone for being occasionally a little over-dressed is by being always absolutely over-educated. -Oscar Wilde
And another question. I often wonder why (particularly in training) you only want the piezo and/or LED to light for a second or so?
In my mind, the following would be a better approach:
On registering a hit, the piezo and LED go off;
The piezo goes off after a second or so; but
The LED stays on until you reset it.
I find that when many fencers are fencing electric, and buzzers go off regularly, it is good to keep your score until you manually reset it.
As for makeing the Epee bell grounded, that's much more difficult. It's eassy when the two fencer share a circuit, but in the case of wireless boxes there's no way to make the bell any different than anything else. That's why these are good for practice, but not competition.
Originally Posted by mhoneth
And another question. I often wonder why (particularly in training) you only want the piezo and/or LED to light for a second or so?
Mostly out of conveneience. To do this requires only one 555 timer. It's certainly possible to make the LED latch, that requires a second chip.
If you want to latch it, here's what comes to mind: Get a basic D-flip flop (You'll probably see edge triggered on there somewhere) and tie the LED to the Q output. Tie the D input to +9V and the 555 output to the CLK input. Add a push-button that connects the RESET input to +9V. You'll probably have to get a CMOS chip, since most TTL tops out at 7V.
If you're creative, you can get a 556 timer, and use the second half of the chip to latch it.
-Pepster
- Captain Solder to the Rescue!
Last edited by Pepster; 05-21-2004 at 03:13 PM.
Reason: Fix quote
If it were easy to make those buzzers not go off on bell guards, we would have tons of wireless fencing everywhere. Basically you have to tell the buzzer box the difference difference between hitting metal and hitting flesh/clothing. When using a simple buzzer box, an épée tip is just like a simple button or switch. There are no sensors on it that could determine what exactly "flipped the switch."
To make things ever clearer, try turning the lights at your house on and off. Is there a way for the light switch on the wall the know whether you used your hand or foot or an épée bellguard? Your épée tip works just the same way. It does not "care" who depressed it. All it knows is that it is depressed, and that the buzzer should sound.
I'm not an electronics buff, but here is my thinking on the guard problem:
All the buzz boxes I've seen only use the A & B prongs to complete a circuit, the C prong (which grounds the guard through the body) could potentially be isolated from the body, giving the guard a different potential compared with ground. A buzz box incorporating the C prong would then be able to measure a resistance distinct from ground.
I'm not an electronics buff, but here is my thinking on the guard problem:
All the buzz boxes I've seen only use the A & B prongs to complete a circuit, the C prong (which grounds the guard through the body) could potentially be isolated from the body, giving the guard a different potential compared with ground. A buzz box incorporating the C prong would then be able to measure a resistance distinct from ground.
Keep in mind that you're wanting to ground your opponents bellguard, and there is where the problem lies. For your opponent's bellguard to communicate with your buzzer box, there has to some physical connection between them, ie a wire. If you use the C prong, in some way, then it would only affect YOUR bellguard, not your opponent's.
I've been fooling around with a 555 timer circuit, and it seems to work perfectly fine with an LED. However, if I connect a Piezo buzzer to the circuit, the buzz time is highly inconsistant. Does anyone know the equivalent circuit of a piezo buzzer? I hope someone is knowledgable about this stuff.
the problem is that the output from a 555 is of insufficient voltage/current. Connect the out to the middle pin of a PNP transistor and use the larger voltage directly from the battery.
The only way to atone for being occasionally a little over-dressed is by being always absolutely over-educated. -Oscar Wilde
Originally Posted by mhoneth 