It's Alive - Progress Direct Systems Volt Tattler 2 Owner's Manual

It's Alive

If the Green LED is flashing then Volt Tattler 2 is taking readings. If the Volt Tattler made no sounds at
power up (no Morse 'R', .-.), there must be some problem with the 2N3904 circuitry. Check the
orientation of the transistor. Check that the speaker is inserted and properly soldered. The speaker can
be installed in either polarity. Look for shorts and bad solder joints in the transistor (Q1) and speaker
area components.
It's Whining
If the Green LED is flashing periodically and we have sounds that are not recognized check the following:
If the programming button is shorted the Volt Tattler 2 will announce its version number in Morse code
at power up. It will then go to the high threshold programming mode and stay there. This is quite noisy.
Power down and look for a short across the Programming Button.
If at power up we hear the Morse "R" followed by a series of 'H's or 'L's we need to check the incoming
voltage to see if it is outside the thresholds. If it is high or low we can adjust the power supply voltage
between the thresholds to stop the annunciations. Remember that a new Volt Tattler 2 will have a low
threshold of around 10 volts and a high threshold around 15 volts.
It's Whining Inappropriately
If the Volt Tattler 2 is announcing a bad voltage level, yet we measure one that is fine, there may be a
problem with resistors R1 and R2. If either resistor is incorrect the voltage that the microcontroller sees
will not be the correct ratio of the power supply voltage. This can cause ether high or low sounds to be
inappropriately generated. Using our volt meter we can see if the readings are getting to the proper
microcontroller pin. Use the high input impedance voltmeter, such as a digital voltmeter or FET analog
voltmeter, to make these measurements. Pin 3 is the analog input that is to be measured to check R1
and R2. The voltage at that pin will be approximately related to the power supply voltage as follows:
V(Pin3) ≈ V(PowerSupply)/13
This will be approximate as it is governed by the ratio of R2 to (R2+R1).
For example if we are feeding the board with 13 volts, the voltage at R2 (Pin 3 of the microcontroller)
should be about 1 volt. If the power supply voltage is 26 volts then that voltage should be about 2 volts.
If Volt Tattler 2 sounds repeated Morse question marks '?'attempt to recalibrate the thresholds. If that
does not fix the repeated question mark sounds then there is a major problem with the microcontroller
and it will need to be replaced.