Newb Questions - One lead outputs from schematics?

[Siike92]

Newb Questions -- One lead outputs from schematics?

Hey there PF, I just recently got into electrical engineering and created a voltage controlled oscillator and control voltage keyboard to go with it(the goal is a modular synthesizer). I've visited quite a few sites and learned a lot so far, but there are also a few questions that can only be answered by someone who knows what they're doing. For example, when I created my voltage controlled oscillator, it was a modified version of this schematic, http://ecelab.com/circuit-vco-555.htm.

I wanted an 1/4" audio jack for the control voltage and another audio jack to replace the speaker as well. This was simple in this schematic because it was clear where to connect the audio jack leads since there were clear "in"(+) and "out"(ground) points.

However, a great deal of schematics I come across like these ones, http://www.kpsec.freeuk.com/555timer.htm#monostable, have only one lead for outputs. How am I supposed to connect an 1/4" audio jack for this output? The trigger and reset have both leads, why not the output?

Anyway, it would be great if someone could help me. I'm very confused. Thanks a lot in advance! And please forgive my newbiness, I'm trying very hard to get past it.

 

[vk6kro]

The output does consist of two leads.

The one marked "Output" and the negative lead of the power source marked "0V" on the diagram.

 

[Siike92]

So then anytime a schematic seems to only have one output lead, the other lead is ground? Is that always the case? What about with input leads, I've seen a few schematics with only one input lead.

 

[vk6kro]

Yes, it usually applies. I can't think of any common exceptions.

Microphones will usually be connected with a shielded cable and the shield will always be connected to a
"ground" point in an amplifier, which might be the metal case the circuit is in, or it might just be a common area on the printed circuit board which is also used as one side of the output voltage.

Mostly, it is also the negative side of the power supply.

 

[Siike92]

Thanks a lot for the help!