Protecting the Function Generators
-----------------------------------
It is possible to damage function generators if the
user is not careful about watching for DC voltage levels
either on the output of the generator, or present in any
circuit node to which the generator is connected.  This can 
happen when you:

- Have a DC offset voltage on the generator's output

AND/OR

- ...you connect to a low-impedance DC voltage source
on your circuit. 

Under these circumstances the output amplifier stage of 
the generator and the voltage source in your circuit may
"fight", and the function generator will probably lose. 
Most are designed with a 50 ohm output impedance and are
cannot supply significant output current, so don't try
to use the generator's DC capabilities to power your circuit.

Most if not all of the generators in the UNL EE student
labs are equipped with resettable output protection fuses.
When connected incorrectly as described, these fuses may
blow and the output will be disabled.  Once the generator
is disconnected from the problem and allowed to cool, the
fuse should reset itself.

So we suggest:
- Don't use a DC offset on the output if you don't really need
it.
- Measure whether the circuit point to which you are connecting
has a DC level.
- if it does, it is a good idea to isolate the DC level by running
the output of the generator through a capacitor and then into your
circuit.  (Use 1 ufd or larger if possible to reduce frequency-
dependent effects.)