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a good start is to post some pictures of your board
list any component changes you have made if any
provide some measurements from various parts of the circuit
It will always be ringing if there is no -5V supply. This suppy is generated from the transmit circuit.
The transmit circuit is a basic oscillator which requires the coil to be connected so this means that if you do not have a coil connected, there will be no -5V supply and your buzzer will always be on.
If you're like me and don't yet have a coil made then you will need to either buy a 6 mH choke and connect it temporarily in place or make a dummy one (which is what I did) by winding about 100 ft of 30 AWG magnet wire around a former. I used this calculator: http://www.pronine.ca/multind.htm
to get a ballpark but it was only a very rough guide and in reality, I needed quite a few more turns than this indicated.
a good start is to post some pictures of your board
list any component changes you have made if any
provide some measurements from various parts of the circuit
Has anyone considered replacing this -ve rail supply with a proper regulated one?
Hi Farside
yes but to what gains, by doing that you would draw more current out of the battery, at least 50ma maybe more.
I will say though in the early days while fault finding on the TGSL I did use the -5v from my bench supply.
Start by double checking the alignment of the chips.
Then power it up while closely measuring the current draw from the main supply in case you have any shorts.
Then test the various voltage rails to confirm they are there. 12V, 8V, -6V.
Then check that all the IC's have power to their respective pins (U6, pin 4 and 11 for instance).
There's not much else you can do with the multimeter.
satdaveuk: I'm planning to experiment with the tx frequency and figure it's likely going to effect the -ve voltage level. I also don't like the idea of the entire system reliant on the connection of the Tx coil... then again without a Tx coil connected, the system is useless anyway
Start by double checking the alignment of the chips.
Then power it up while closely measuring the current draw from the main supply in case you have any shorts.
Then test the various voltage rails to confirm they are there. 12V, 8V, -6V.
Then check that all the IC's have power to their respective pins (U6, pin 4 and 11 for instance).
There's not much else you can do with the multimeter.
satdaveuk: I'm planning to experiment with the tx frequency and figure it's likely going to effect the -ve voltage level. I also don't like the idea of the entire system reliant on the connection of the Tx coil... then again without a Tx coil connected, the system is useless anyway
ha ha lol
anythings worth trying for improvement go for it let me know im all ears
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