Hi Steve, I've had a read through the first part of the book and hopefully getting my components tomorrow.
I wanted to ask a few things:
What is the purpose of the negative terminals which are connected to the ground rail in the terminal blocks where the probes are attached? As far as I can see nothing is actually connected into these negative terminals from outside the project box (like probes etc). I know the positive terminals on these blocks have the circuit probes connected. I suppose the question is why are they connected to the ground rail?
Is the function of the connection to the ground in the circuit to provide a route for excess current created when the diodes need to open up to limit voltage? I.e. if voltage limiting were not needed could this part be omitted altogether. I feel like it could not as I know production oscilloscopes have a ground connection probe too. I think it may be that the connection to ground is there so that the potentiometer forms the voltage divider along with the 470k resistor. So the 100:1 divider you mention in the book is the series resistance of the 470k resistor plus the 4.7k from the 'top' half of the potentiometer against the 4.7k of the 'bottom' half of the potentiometer which is linked to gound. Is that right?
Can the signal generator in the second part of the book be used to generate signals to input into other circuits that I might make e.g. can it create square wave, triangle waves and the like?
Sorry if these are all noob questions. I like to understand things as otherwise I won't be able to do things on my own in the future.
Thanks,
Hi Robert,
Don't worry about asking questions. Nobody knows everything, me included.
In order to measure an electrical signal you need two connections to complete the circuit. A ground or negative connection is generally used to create the connection. So to display an AC signal you would connect the ground of the probe to the ground or negative side of your unit under test and use the positive connection to probe the signals in your circuit.
The voltage limiting is there to help protect your PC against inadvertently applying too high a voltage to the probe. Please remember that it will not protect you if you apply very high voltages so you should stick to signals below 30V to be on the safe side.
The signal generator can indeed be used for purposes other than calibrating your oscilloscope probe. You can use it for instance as a convenient signal source when testing audio amplifiers. By injecting a known waveform into the input of the amplifier and monitoring both the input and the output with the oscilloscope you can not only see how much gain the amplifier is providing but also how faithfully the circuit reproduces the wave shape at the output.
Steve
about the capacitor helping.
