# What does this strange symbol refer to?

I am referring to the symbol with +4V next to it. Seems like a voltage source to me. I just haven't seen this anywhere before.

• There is a voltage source(rail) of 4V here. I don't see any other that looks like one. – Eugene Sh. Mar 31 '15 at 18:51
• I misspelled symbol. So it's just an ordinary Voltage source. What is its polarity? – Shemafied Mar 31 '15 at 18:52
• OK, I see the problem now. Let me think how to address it.. – Eugene Sh. Mar 31 '15 at 18:53
• You're trying to identify a symbol by explaining what it looks like to you!? Actually stop and think about it. How are we supposed to know what you think a symbol looks like, especially when you've already stated you don't know what it is? Duh. – Olin Lathrop Mar 31 '15 at 19:00
• In addition to this question: The upper triangle... is it called a POSITIVE GROUND symbol??? or there is a some-other name for this symbol? – Always Confused Jul 1 '16 at 19:14

Strictly speaking, it is not a full circuit, but an equivalent full circuit can be easily derived from it, because it has the full information. It has two "labels" (which are not an actual components), which are denoted with the GND symbol (the bottom one) and the triangle symbol (the top one). Both are denoting the voltage levels of the nets they are connected two. The ground is denoting the voltage of 0V (reference potential, to be precise), and the triangle is the denoted (+4V) voltage relative to that reference. The equivalent circuit would look exactly like this one but with a 4V power supply with "+" connected to the triangle, and "-" connected to the GND.

I assume you are referring to the top symbol, the triangle pointing up to "+4V". That is showing that the net is connected to a +4 V supply. The other symbols with "R" designators are resistors. The symbol with the "D" designator is a diode, cathode to the left, anode to the right. This means current can flow thru it right to left but not left to right.

• I think the OP having trouble with not seeing a literally "closed" circuit, having a power supply as a single unit. – Eugene Sh. Mar 31 '15 at 18:59
• Indeed, I was referring to that symbol but it got edited out of my question. What's bothering me now however is your statement that the net is connected to +4V . Does that mean that we could just put a battery there, or that th voltage difference between ground and the source is +4V? – Shemafied Mar 31 '15 at 19:02
• @Eugene: Maybe, but that's not even close to what he asked. – Olin Lathrop Mar 31 '15 at 19:03
• @Shemafied It just means that that net is 4V above ground. – Golaž Mar 31 '15 at 19:04
• The "+4v" is implicitly with respect to ground. In other words, one realization of that circuit is with a 4 V power supply connected between the top node and ground. – Olin Lathrop Mar 31 '15 at 19:05

That upwards pointing triangle symbol represents a power terminal in labcenter proteus.

By default in projects the terminal is connected to VCC net (5v) but can easily be connected by the user to any other power rail, even negative ones (referenced to the ground).

Another option if for a user to asign a voltage directly to the terminal by typing a number as a label with a + or - sign in front of the number for positive and negative voltages respectively.

A +4 represents a 4v voltage source referenced to the ground, it's the equivalent of connecting a 4v battery or voltage source between the power terminal and ground.