Need help reading a schematic.

[budm]

Re: Need help reading a schematic.

The output of the PIC PIN 2 net label K1 goes to the resistor R3 on the leg the resistor with net label 'K1' to turn on the the Transistor Q1 which drives relay K1 coil.
Pin 1 net label 'K2' of the PIC goes to R4 to turn on Q2 which drive K2 coil.
You have component designator, I.E.: K1, R1, C1, etc.

[Spork Schivago]

Re: Need help reading a schematic.

R2 is a 16 ohm resistor. I don't know why the value isn't listed on the schematic.

[Spork Schivago]

Re: Need help reading a schematic.

It's a bit of a Euro schematic - and some people like to run wires all over and some like to use Nets.

I think you are getting mixed up with component pin names and net labels. Also Belgium has three official languages: Dutch, French, and German so abbreviations are tough to figure out. You would have to ask what "S" and "O" mean in that language.

The contrast pot has pins A,E,S (in English usually CW clockwise, CCW, wiper/slider) and the wiper pin "S" goes to Net CONTRAST which only goes to the LCD header pin 3. So the pin name "S" and Net name "CONTRAST" are connected to each other.

The relays have pins O,S,P (in English NC, NO, COM) and here the "S" pin goes to connectors X#-2. It has no connection to the "S" pin on the trimpot because they are different components.

PIC K1 and K2 Net labels (signals) only go to the 1k resistors. Their (Net) name is confusing with components K1 and K2 and not the clearest way to do a schematic.

The common terminal on the relays "P" go to connectors X3-1 and X5-1 only. Not the PIC - you don't want the PIC getting high power going to its pins.
Resistor R2 sets backlight LED current but has no value.

Thanks! So the K1 and K2 on the PIC go to the K1 and K2 net names on the 1K resistors. It is a bit confusing, because the relay's have names called K1 and K2 on the board layout but the schematic is using K1 and K2 as net names and the PIC has a K1 and K2. A bunch of K1 and K2's! Thanks for all the help guys!

[redwire]

Re: Need help reading a schematic.

It's a bit of a Euro schematic - and some people like to run wires all over and some like to use Nets.

I think you are getting mixed up with component pin names and net labels. Also Belgium has three official languages: Dutch, French, and German so abbreviations are tough to figure out. You would have to ask what "S" and "O" mean in that language.

The contrast pot has pins A,E,S (in English usually CW clockwise, CCW, wiper/slider) and the wiper pin "S" goes to Net CONTRAST which only goes to the LCD header pin 3. So the pin name "S" and Net name "CONTRAST" are connected to each other.

The relays have pins O,S,P (in English NC, NO, COM) and here the "S" pin goes to connectors X#-2. It has no connection to the "S" pin on the trimpot because they are different components.

PIC K1 and K2 Net labels (signals) only go to the 1k resistors. Their (Net) name is confusing with components K1 and K2 and not the clearest way to do a schematic.

The common terminal on the relays "P" go to connectors X3-1 and X5-1 only. Not the PIC - you don't want the PIC getting high power going to its pins.
Resistor R2 sets backlight LED current but has no value.

[Spork Schivago]

Re: Need help reading a schematic.

The wiper of the pot P1 pin S (net label named 'Contrast') is connected to the LCD1 connector pin 3 (net label named 'Contrast'). As you can see there are only two net label with the same name 'Contrast' so those to are electrically connected together. You should learn more about net label to understand what it is and what it is used for in the schematic.
Do not get confuse between the component pin names with net label.
For example the pot P1 as shown in the diagram, there are 3 electrical pins: pin 'A', pin 'E', and pin 'S'.

I gotcha Budm! I am a little familiar with net names and that's where my confusion came from. I thought there where two separate net names, S and CONTRAST. Like the potentiometer was connected to both signals. Does that mean for the stuff down by K1 and K2, they're just pin labels as well? The O, S and the P? Would they just be the labels for NO, NC and COM? The relay's are JS12N-K 1 pole power relays.

I'll do a bit more research on the net labels as well. Thank you!!!

[budm]

Re: Need help reading a schematic.

The wiper of the pot P1 pin S (net label named 'Contrast') is connected to the LCD1 connector pin 3 (net label named 'Contrast'). As you can see there are only two net label with the same name 'Contrast' so those to are electrically connected together. You should learn more about net label to understand what it is and what it is used for in the schematic.
Do not get confuse between the component pin names with net label.
For example the pot P1 as shown in the diagram, there are 3 electrical pins: pin 'A', pin 'E', and pin 'S'.

'Also, for X3-1 and X5-1, do I just tie them together because they both say O and then send them off to the PIC where it says K1 and K2? And what does the P stand for under K1 and K2? Is that just the power to the relays?'
'do I just tie them together' No.
Relay has 5 pin names: Pin '1' and Pin '2' are for the relay coil, then there are 3 pins for the relay contacts, Pin 'P' is the Common pin, Pin 'O' is the Normally Closed contact, pin 'S' is the normally OPEN contact. When the relay is energized, the pin 'P' will then make contact with pin S', pin 'O' is then no longer make contact with pin 'P'.

[Spork Schivago]

Hello,

I'm trying to learn how to build circuit boards. I ordered a kit off the net for a digital timer. Essentially, it's powered by a PIC and it has an LCD screen that gets connected to it. You program an amount of time and then it will provide power to another board that has a bunch of UV LEDs on them. You just use transparencies and photoresist boards with this kit and you get real nice circuit boards I guess.

Anyway, I've downloaded Eagle and I'm trying to create a schematic for the timer board. The guy who sells the kits provide schematics and board layouts, but they're all in PDF format. Eventually, I'd like to modify the design a bit so the power supply and the timer are all on one board.

I'm having trouble reading the schematic though. I've attached a copy. They use some different symbols, European ones I think they are. But I have a few questions I was hoping some one could help me out on. On the potentiometer located at A-6 (upper right corner), I see there's a pin that says S CONTRAST. And a bit further down in the schematic (B & C 4 - 5) there's some screw type connectors (to hook wires up to) that say X3-2 and X5-2. They both say S. Does the potentiometer go to both of those S's and to CONTRAST on the 16-pin header for the LCD screen?

Also, for X3-1 and X5-1, do I just tie them together because they both say O and then send them off to the PIC where it says K1 and K2? And what does the P stand for under K1 and K2? Is that just the power to the relays?

Any help would be greatly appreciated. Thank you.