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Step 7Test, Mount Board
You may want to test the board before you mount it. I assume you've already got a source of Audiostrobe signals; hence your only reason to build this project. If not, look in the last step for a list of software that can generate these signals for you. For now, just use the test file I've provided. It's m4a, not mp3, but Winamp and Media Player should both play it without a hitch. I'd assume most other media players would as well. Encoding to mp3 apparently cuts the carrier signal out. I haven't experimented with that, so it may just be my settings. I'd recommend burning the file to cd and using an old portable cd player for testing and the first couple of times using the unit, just to be safe.
If the LED doesn't light:
If the LED lights, you're ready to try the unit out. If you've already built the LED glasses that accompany this unit, turn the power off and plug them in. Otherwise, you'll need either an analog multimeter or an oscilloscope to check the operation. Digital multimeters will not work. Play the audiostrobe file I've provided. If you're listening through the headphones, don't be alarmed by the highly obnoxious nature of the tones. The actual audiostrobe signal is inaudible to most humans; I made the tone sound this way so I could see how the audiostrobe pulse was syncing with the audio tones. It doesn't usually sound like that :)
If you've got the glasses plugged in, the LEDs should flash briefly when you first power on the circuit; if they don't, check the line selection switch. If you're using an analog multimeter, the needle should jump upon power up. If you're using an o-scope, I'm going to assume you know enough to not need instructions from here on out.
The file starts out with a very quick pulse that ramps down to around 1hz within a few seconds. You'll hear it in the audio. The rate then smoothly begins to ramp up, about 1hz every six seconds, if I remember correctly. So the LEDs should be flashing about once per second immediately after the ramp down, twice per second six seconds after that, three times per second six seconds after that, etc. The file runs about two and a half minutes. Whether you're using the glasses, the multimeter, or the scope, you should be seeing the pulses. If you're not, and you can hear the tones, try turning up the volume. There's a minimum threshold for the circuit, and in this particular file, the audio tones are extremely loud, even uncomfortable. If that works, don't worry; you won't have to listen to all audio at that volume.
If it doesn't work, and you've passed all of the above tests, you're in for some basic electronic troubleshooting, which unfortunately is beyond the scope of this instructable. The only quick suggestion I have would be to check the voltage between the negative battery terminal and pin 4 of IC1. The voltage should be about 5 volts. If it's not 4.5-5.5V, the problem is likely with IC2, the voltage regulator. Otherwise, the most likely culprits are the electrolytics, especially if you bought them surplus or removed them from old equipment, or the tone decoder itself.
Hopefully the unit passed the above tests. So now you get to shoehorn the board into the tin. It won't be easy (unless you drilled your holes waaay oversize). The easiest way I've found is to insert the end with the two jacks first, pointing them into their holes. Bend the wall of the tin above the audiostrobe jack hole outwards to allow the jack to pass into the tin. Start maneuvering the PCB into position, alternating between trying to slide the left end of the PCB (with the two jacks) into position and lowering the right end of the board. Once the barrels of the two jacks are in their holes and aligned correctly, the board will usually just pop into place.
Before you secure your switches, screw down the board. I cannot stress enough the need to be gentle when tightening your screws. Finger tight, no more. The washers shouldn't move when you poke them with tweezers, but neither should there be indents in the board. Then repeat the above tests. If the board fails, either you've got a short somewhere or you broke something installing the board. If the LED glasses light up and stay lit, your audiostrobe jack barrel is almost certainly shorting to the tin. You'll have to remove the board and reinstall your electrical tape.
Once everything's working correctly, mount your switches and position your LED. Pop in the battery and close the case. Use an X-Acto knife to trim the electrical tape flush with the ends of the jack barrels. You'll need something to brace the battery against the case. I originally had visions of foam rubber strategically glued to the wall, but in the end, folded paper won me over with its simple, yet sleek and modern appeal.
- First, with the power disconnected, check with a multimeter to make sure you've got a connection from each pin on the line input jack to the corresponding pin on the headphone jack.
- Check the resistance from the barrel of the line input jack to the barrel of the audiostrobe jack. It should be around 1k Ohms. If it's open, there's a problem; if it's a dead short, there's a problem.
- Double-check your polarities, especially on the electrolytics and the 7805. C5 is closest to the edge of the board; its negative stripe faces the edge of the board. C6 and C7 butt up against each other; their negative stripes face each other. The 7805's metal tab should be flat against the board.
- With the power still disconnected, connect the line input to an audiostrobe source. Plug some headphones into the headphone jack. You should hear the audio. If not, well, I don't know what to tell you. You already checked the connections to the jacks. Check 'em again.
If the LED doesn't light:
- Check for voltage between the battery connectors (not terminals)
- Check LED1's polarity.
- Check for voltage between the negative battery terminal and the LED lead that's farther away from the battery. If there's at least 2.2v, the LED's polarity is wrong or it's bad. If there's voltage, but less than 2.2v, either you've got the wrong resistor value for R3, the battery's almost dead, or you've got a connection problem (likely a shorted component). If the resistor is correct and the battery's fresh, check all of your connections for bridges.
- If there's no voltage, check for voltage between the negative battery terminal and the lead of D1 that's facing away from the battery (the one with the polarity symbol). If there's voltage (around 7.5-8V), you've likely got an open somewhere in the circuit. Start looking for unsoldered connections or broken traces.
- If there's no voltage at D1 check the polarity. If the polarity's correct, check for voltage on the side of D1 that's facing the battery. If there's voltage there, D1 is bad. Replace it with a diode that can handle more current.
If the LED lights, you're ready to try the unit out. If you've already built the LED glasses that accompany this unit, turn the power off and plug them in. Otherwise, you'll need either an analog multimeter or an oscilloscope to check the operation. Digital multimeters will not work. Play the audiostrobe file I've provided. If you're listening through the headphones, don't be alarmed by the highly obnoxious nature of the tones. The actual audiostrobe signal is inaudible to most humans; I made the tone sound this way so I could see how the audiostrobe pulse was syncing with the audio tones. It doesn't usually sound like that :)
If you've got the glasses plugged in, the LEDs should flash briefly when you first power on the circuit; if they don't, check the line selection switch. If you're using an analog multimeter, the needle should jump upon power up. If you're using an o-scope, I'm going to assume you know enough to not need instructions from here on out.
The file starts out with a very quick pulse that ramps down to around 1hz within a few seconds. You'll hear it in the audio. The rate then smoothly begins to ramp up, about 1hz every six seconds, if I remember correctly. So the LEDs should be flashing about once per second immediately after the ramp down, twice per second six seconds after that, three times per second six seconds after that, etc. The file runs about two and a half minutes. Whether you're using the glasses, the multimeter, or the scope, you should be seeing the pulses. If you're not, and you can hear the tones, try turning up the volume. There's a minimum threshold for the circuit, and in this particular file, the audio tones are extremely loud, even uncomfortable. If that works, don't worry; you won't have to listen to all audio at that volume.
If it doesn't work, and you've passed all of the above tests, you're in for some basic electronic troubleshooting, which unfortunately is beyond the scope of this instructable. The only quick suggestion I have would be to check the voltage between the negative battery terminal and pin 4 of IC1. The voltage should be about 5 volts. If it's not 4.5-5.5V, the problem is likely with IC2, the voltage regulator. Otherwise, the most likely culprits are the electrolytics, especially if you bought them surplus or removed them from old equipment, or the tone decoder itself.
Hopefully the unit passed the above tests. So now you get to shoehorn the board into the tin. It won't be easy (unless you drilled your holes waaay oversize). The easiest way I've found is to insert the end with the two jacks first, pointing them into their holes. Bend the wall of the tin above the audiostrobe jack hole outwards to allow the jack to pass into the tin. Start maneuvering the PCB into position, alternating between trying to slide the left end of the PCB (with the two jacks) into position and lowering the right end of the board. Once the barrels of the two jacks are in their holes and aligned correctly, the board will usually just pop into place.
Before you secure your switches, screw down the board. I cannot stress enough the need to be gentle when tightening your screws. Finger tight, no more. The washers shouldn't move when you poke them with tweezers, but neither should there be indents in the board. Then repeat the above tests. If the board fails, either you've got a short somewhere or you broke something installing the board. If the LED glasses light up and stay lit, your audiostrobe jack barrel is almost certainly shorting to the tin. You'll have to remove the board and reinstall your electrical tape.
Once everything's working correctly, mount your switches and position your LED. Pop in the battery and close the case. Use an X-Acto knife to trim the electrical tape flush with the ends of the jack barrels. You'll need something to brace the battery against the case. I originally had visions of foam rubber strategically glued to the wall, but in the end, folded paper won me over with its simple, yet sleek and modern appeal.
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