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Author Topic: need help reading a few symbols on a schematic  (Read 733 times)
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Kamchatka, Russian Federation
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ok. in the first picture, the audio xformer (in the circle marked 'A') i have the device. it's a radioshack #273-1380 audio xformer. it has four wires.. i can figure out the names for them via a datasheet, no problem. but that symbol in the schematic looks weird, how do i hook it up?

next, is B. it looks like a simple power circuit.. but why do i need to wire it to ground between the batteries.. and isn't the batteries already ground and voltage? so.. i would just be wiring that one battery to itself.. which is dangerous.

C. U1a and U1b are IC chips. i don't know what that symbol means though. does the plus and minus refer to certain pins? the only thing i'm certain is that the tip of the triangle must correspond to the 'output' pin. if you need a datasheet, the IC is a 'dual op amp' radioshack # 276-1715

D. again, this is an xformer.. radioshack #273-1380 although this time, it looks like this xformer only has two wires. the other one had 4. mind you, i haven't bought this yet.. the only picture i have is on the radioshack website there.

and where the big X is, i'm using an arduino circuit instead of that very costly precision waveform generator chip.

the second picture is just so if you can't see clearly under my writing in the first.

onto the third picture

i have two questions here...

1. the part of the circuit labled 'AMP' it looks like a potenimeter? but both amp chips i have are chips. so, what does that mean?

2. while i know what a normal capasitor looks like, i don't know what i'm supposed to do here. instead of just the two lines going paralell, one is a semicircle.. and the other is straight.. then there is a + sign above it. what does that mean? is there a difference between the normal capasitor symbol and this one?


i thank anyone who can give me tips on this


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* experimenters neurophone.gif (10.38 KB, 850x377 - viewed 38 times.)

* F8002POH9T4R08A.MEDIUM.jpg (26.77 KB, 620x319 - viewed 49 times.)
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i thank anyone who can give me tips on this

(A) The transformer has a primary and secondary winding. The dot signifies the direction that the windings are made.

(B) The Op-amp needs a plus and minus (relative to ground) power supply. One battery provides the plus, the other provides the minus. Both are referenced to ground.

(C) The + and - symbols are "Non-inverting" and "Inverting" inputs, respectively. Read up on how op-amps work to understand this. It's too much to go into in this post. And yes, the right hand "tip" of the triangle is indeed the output.

(D) Transformer "D" needs to have 4 wires. Your 2 wire part will not work.

As far as the third picture... it's too small and fuzzy to even read. I'm guessing maybe it's some kind of an R/2R resistor ladder (cheap D/A circuit) and a little audio amp? It's hard to tell.

Lastly, capacitors: The semi-circle denotes a polarized capacitor, negative side. Like this:

(positive) + -------|(------- - (negative)

Hope this helps.
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ok. in the first picture, the audio xformer (in the circle marked 'A') i have the device. it's a radioshack #273-1380 audio xformer. it has four wires.. i can figure out the names for them via a datasheet, no problem. but that symbol in the schematic looks weird, how do i hook it up?

Look at the picture on the Radio Shack website:

http://www.radioshack.com/product/index.jsp?productId=2103254

See how on the transformer the blue and green wire exits from one side, and the red and white wire exits from the other (far) side in the picture? Those correspond to each of the two "sides" on the schematic. The rounded bumpy lines on the symbol represent the coil on each side of the transformer; notice the lack of anything between the coils on the schematic - this generally means it's an air-gap core, or at least a non-ferrous core (if it were to have an ferrous core, there would be double lines between the coil lines on the symbol). I notice that there's no numbers or ratio shown on the symbol, so likely this is just a matching transformer, so either pair of wires may be connected for either side; however, you must wire the same opposite pair of wires on the "+" side to ensure polarity of the signals being passed (ie - the top wires on either side could be green and white, while the bottom could be blue and red). I hope that makes sense.

next, is B. it looks like a simple power circuit.. but why do i need to wire it to ground between the batteries.. and isn't the batteries already ground and voltage? so.. i would just be wiring that one battery to itself.. which is dangerous.

No - what you are looking at there is called a double-ended power supply: You connect the two batteries in series (in this case, a pair of 9 volt PP3 batteries), then tap the center of the series connection for your ground reference. Then - the negative pole of one of the batteries become -9 volts DC, and the positive pole of the other battery is +9 volts DC. The reason you need this for this circuit, is because the dual op-amp IC used (#276-1715) requires a dual-ended power supply; ie, one capable of providing both positive and negative voltage levels. The rest of the circuit - wherever a ground symbol is shown - MUST be connected to the ground reference of that center tap.

C. U1a and U1b are IC chips. i don't know what that symbol means though. does the plus and minus refer to certain pins? the only thing i'm certain is that the tip of the triangle must correspond to the 'output' pin. if you need a datasheet, the IC is a 'dual op amp' radioshack # 276-1715

Yes - see this datasheet - page 3 (TL082 - top middle pinout diagram):

http://www.ti.com/lit/ds/symlink/tl082.pdf

VCC+ ( pin 8 ) goes to the positive voltage supply output, VCC- ( pin 4 ) to the negative voltage supply output. For one of the op-amps in the schematic, 1IN+ ( pin 3 ), 1IN- ( pin 2 ), and 1OUT ( pin 1 ) are connected, and for the other op-amp, 2IN+ ( pin 5 ), 2IN- ( pin 6 ), and 2OUT ( pin 7 ) are connected; the "+" and "-" symbols on the op-amp schematic symbols indicate which you connect; there are two op-amps in the IC corresponding to the two op-amp symbols on the schematic. The +V and -V symbols near the op-amp symbols on the schematic indicate to hook up to the dual-ended supply in your diagram marked "B".

D. again, this is an xformer.. radioshack #273-1380 although this time, it looks like this xformer only has two wires. the other one had 4. mind you, i haven't bought this yet.. the only picture i have is on the radioshack website there.

I'm not sure where you get that it only has two wires; the picture I am looking at, the same one I indicated earlier and linked two - has 4 wires; the transformers are identical - they are just used as impedance matching transformers for audio signal transfer purposes. Is there something I am missing?

and where the big X is, i'm using an arduino circuit instead of that very costly precision waveform generator chip.

the second picture is just so if you can't see clearly under my writing in the first.

onto the third picture

i have two questions here...

1. the part of the circuit labled 'AMP' it looks like a potenimeter? but both amp chips i have are chips. so, what does that mean?

I can't see your third picture clearly - it is too small, and blurry, so I don't know what you are meaning...?

2. while i know what a normal capasitor looks like, i don't know what i'm supposed to do here. instead of just the two lines going paralell, one is a semicircle.. and the other is straight.. then there is a + sign above it. what does that mean? is there a difference between the normal capasitor symbol and this one?

This is easy to answer, simply because it is a common part: What you are looking at is the symbol for a polarized electrolytic capacitor. These capacitors typically look like small "cans" (see the second picture here):

http://en.wikipedia.org/wiki/Electrolytic_capacitor

Note the "-" symbol on the capacitor body in the picture; notice how it is near one of the leads. That lead is the "negative" lead, and the other lead is the "positive" lead, and it must be oriented properly to the schematic in order for it to work (the "+" symbol on the schematic is likely near one or the other lines leading away from the capacitor - unfortunately, I can't see it due to the reasons stated above). If you don't orient it properly, bad things can happen, depending on what it is being used for (for signal filtering, maybe not much; when used for power filtering, you can get a small explosion, fire, smoke, etc!).

The other symbol for a capacitor you are referring to - with parallel lines - refers to a non-polarized capacitor; which may be oriented in either direction without any problems. A common type is the so-called ceramic capacitor family (there are many others):

http://en.wikipedia.org/wiki/Ceramic_capacitor

Hope that helps...
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Kamchatka, Russian Federation
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thank you both, that really helped me out quite a bit. the only thing i still don't get is the power circuit.. marked B on the diagram. how would i orientate the batteries? what is ground then?
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The short fat line on the battery is the negative of the battery, the longer thinner line is the positive.

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what is ground then?
Anything you want it to be. But on this occasion it would be the junction between one batteries +ve and the others -ve. The two batteries form what is known as a split supply, one with positive and negative rails.
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I'll add that the component marked Amp on the third diagram is, as you state, a potentiometer. It's marked Amp because it adjusts the amplification of the circuit. Turn it one way to increase the volume, the other way to decrease the volume.
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"Amp" stands for "amplitude", not "amplification", I believe.
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ok. thank you very much.. heh. that makes sence
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"Amp" stands for "amplitude", not "amplification", I believe.

Thanks for that correction.
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I found this site to be helpful in the past, It displays a full table of many types of components.
http://www.rapidtables.com/electric/electrical_symbols.htm
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