Help with circuits/schematics

I have some schematics for a project. I can sort of read them, but I need help. If anyone is interested in helping me, my email address is dmontaej@gmail.com, just email me, and I will email you the schematics I'm having trouble reading so you can help me decode them.

Thanks ;D

Just post them or the links here and we can all pitch in. There is nothing like several eyes looking at something.

One question first: where does the Arduino fit into this project?

The reason I ask is that what is on the "switches" sheet could be done in software and only need simple SPST (on-off) pushbuttons. As shown, what that circuit would do is ensure that only one direction output is active at a time. That is, if you push both MovUp and MovDn buttons at the same time, it would turn OFF both outputs. If you push neither, it turns OFF both outputs. But if you push only one, it turns on only that output. If these switches go directly to some other circuit, then this is a good idea. But if the switches only go to Arduino inputs and the software makes decisions from that, then you can save yourself a good bit of hardware by using just a few "if" statements.

I know it could be simpler without the arduino, but the point of the project was to somehow incorporate the arduino, I tried my best, I'm real new to this.

Actually, my point was that it could be simpler with the Arduino. That is the beauty of microcontrollers: a lot of stuff that would have been done with lots of hardware components can be replaced by software.

Oh, okay! Well, my instructor approved of these schematics, so I'm kinda of stuck with them. But I don't know what I need. You think you could help me decode the symbols and list the materials I need?

For the "switches" sheet: 4 of SPDT switches (single-pole double-throw) 4 of 47k resistors; any watt rating is fine, 1/4 watt is very common 2 of 74HC04 chips. (Quad 2-Input NOR gates)

For your relay boards (sheets 3 & 4): 4 of 1N4004 diodes 4 of 2.7K resistors 4 of 330 ohm resistors 4 of LED (your schematic doesn't specify type or color) 4 of SPDT relay with 5VDC coil (DIL = dual in-line, it's a package type that is the same as DIP style chips and is suitable for plugging into a breadboard or solder to printed circuit boards) 4 of BC546 transistors; I'm not familiar with this type. The symbol is an NPN type transistor. There are likely plenty of equivalent transistors, but someone else would have to advise on that.

For the "solar cells" sheet: 1 of TL074CN chip (Quad Op Amp) 1 of 330 ohm resistor 1 of LED

I can't clearly read the resistor values around the op amp symbols. It looks like 10k and 100k. (4 each)

I'm not sure what to use for the DC-DC converter. There should be lots available.

You are amazing. Thank you so much! If I need anymore help, I’ll be sure to post! Or if you don’t mind, can I have your personal email, for if I have an urgent questions. You can just email me at dmontaej@gmail.com and I’ll store you into my contacts. Thanks again!;D

Something else I noticed: those Op Amp circuits can produce a negative output voltage (a voltage below "ground"). You do not want to wire that to the input of an Arduino (or any other microcontroller). Any inputs to the microcontroller, whether to digital inputs or to analog inputs) need to be between 0v (ground) and +5v (Vdd). (Assuming you're using a 5v Arduino) Otherwise the inputs can be damaged.

I'm not sure how to put this without sounding negative, but I don't think its as easy as just toss a bunch of components into a shopping cart and then go build this from this schematics. Well ok it kind of is, but not if you don't know what the components are or does. Seems this schematics leaves some experimenting to be done. On the other hand, it can be a great way to learn :)

But - it would help if you would clarify what you want to do. I would guess a light-following robotic arm (but what kind of light? The sun? A flashlight?) And how you want to finish it, a PCB, stripboard, just the protoboard, something else..?

Plus the schematics leaves some details out, like: - how to (physically) arrange the photo diodes (im guessing thats what it is - yeah I don't know what everything is myself). For a light following something, they would need to be fastened to the moving part. - what kind of photo diode? (It's not a solar cell, but I guess solar cells would work too - but then you'd need to adjust the feedback resistor I guess, or maybe you wouldn't need the opamps at all with solar cells(experiment)). - and more..

Also I'm not so sure about these op-amp circuits either, even if they might work for the author of those. What's the point of the 10k resistor from the op-amp output to ground for instance? Of course it could be my limited understanding of op-amps, but to me it just looks like an unnecessary load. And probably erroneously though to be amplification ratio (Rfeedback/Rimpedance...ish..but I'm only guessing here!) Amplification seems to be depending on the internal resistance of the (unknown) photo diodes. Who's to say you got the same type?

As far as I can see they use a dual voltage source (+V, -V, and ground). That is also something to consider if connecting these to an Arduino analog inputs. Of course you could "fake" a ground at V/2 with a simple voltage divider and yet another op-amp.

And also at least one minor error: It says "Pin 6" (presumably a pin from the Arduino) on the "switches" schematics (MovDnSw) are also on the "Rotate relays and motor drive" schematics (RotLeftDrv). No biggie though, just use another pin.

Like Dilbert98122 says, since you are using an Arduino, I don't see the point of using the swithces circuit at all to prevent you from pushing both up/down or left/right simultaneously (unless you skip the arduino part and connect those directly to the relays schematics). You can prevent that in software. Which you should anyway, as the relays schematics are shortcuts waiting to happen if left/right or up/down are activated simultaneously.

In fact when I think about it, better use of the swithces schematics would be on the output from the Arduino, to be on the safe side (If you want to do it with relays like that).

Apart from the OWI 535 robotic arm which I don't know anything about, I don't really se any very special components here. Maybe the 5V SPST relay. A quick google on "5V DIL SPST relay" or similar should provide some results. Otherwise just resistors, capacitors, diodes, transistors, some logic circuits, LEDs and op-amps..

As an example, the MC34071 is an opamp. LM741 another.. there are hundreds if not thousands to choose from. And I'm not sure if the op-amps needed for the photo-diode (if that is what it is), needs to be of a special kind or not (probably not). 74HC02 is a quad 2-input NOR gates in a DIL package. http://www.kpsec.freeuk.com/components/74series.htm There's also the 4000 (CMOS) series to choose from.. http://www.kpsec.freeuk.com/components/cmos.htm 4001 is yet another quad NOR gate.

Now slightly off-topic: As for asking people to help you via email I think is really misunderstanding the point of a forum. Not to mention pretty "demanding" of people (Sorry I don't know how else to put this in good english). You can't really expect people to work for you like that (unless the pay is good :P). Also, no-one would be able to search and find a possible solution to something similar in the future. Plus, like Mike says, the more eyes the better!

ok rant off :)

Dilbert98122 and theportleygent: Minor correction, as in the end of my last post, its the 74HC02 which is the quad 2-input NOR. 74HC04 is a hex inverter. Just saying.

I have to admit, it’s been a long long time since I’ve done much with op amps. Indeed, that design doesn’t look quite right now that you mention it.

But this is another spot where, depending on the photosensors, you might be able to eliminate a bunch of tricky hardware with software.

The schematic title says “solar cells.” Are these actually going to be solar cells or photodiodes?

Assuming that you’re measuring relative light levels to decide which direction to move, you could probably get by with either CdS cells (photoresistor) or phototransistors instead. Either of which (plus a couple of resistors) could be wired directly to the Arduino analog inputs. You could also then eliminate the DC-DC converter.

Or even with Op amps, you could probably eliminate the DC-DC converter and wire the op amps in a “single-supply” configuration with (as mentioned) a virtual ground. Now this is stretching my memory of op amp circuits, so some others will need to jump in and help out here.

My bad on the chip numbers. I was reading off the schematic. Should have verified.

Or mis-reading I guess.

these are actually solar cells. 4 cells 1 volt, 400 ma. And sorry for the iffy schematics, they were drafted by a friend.

The schematic title says "solar cells."

Oops, missed that one. I just thought the symbols where more diody :D

Assuming that you're measuring relative light levels to decide which direction to move, you could probably get by with either CdS cells (photoresistor) or phototransistors instead. Either of which (plus a couple of resistors) could be wired directly to the Arduino analog inputs. You could also then eliminate the DC-DC converter.

Or even with Op amps, you could probably eliminate the DC-DC converter and wire the op amps in a "single-supply" configuration with (as mentioned) a virtual ground. Now this is stretching my memory of op amp circuits, so some others will need to jump in and help out here.

Good points. Same goes for me and op-amps btw. "virtual ground" was the word I didn't find (in my memory).

these days an "H-bridge" is commonly used to drive a motor in either direction without needing a negative power supply

Yes and you can also do the same thing with relays if you use a relay with dual poles rather than single pole. http://www.thebox.myzen.co.uk/Workshop/Motors_1.html

The switch inputs are very old school, the flip flops on the inputs (those NOR gates) are for removing any contact bounce, something you can so in software and directly connect the switches to the arduino.

Also the op amps as drawn will damage the arduino as they will always produce a negative input. This needs to be eliminated before you try it. It might be good to also add some input protection just in case:-

http://www.thebox.myzen.co.uk/Tutorial/Protection.html Again I am sure you can connect these "photo what ever they ares" direct between arduino input and ground with a 100K pull up resistor.

they were drafted by a friend.

Watch out who your friends are, I would hate to see a circuit drafted by your enemies. ;)

Yes i will watch my back next time. And the original project idea was to build a sun tracker, eventually to power itself.

Just as a reality check, have you been able to power your arm with the solar cells? In series your four cells are only capable of 4v and your arm appears to be 6v. You will probably need a charge pump setup to keep the four D cells charged. The arm itself probably isn't the best setup to be holding solar panels if they have any size to them. You may want to look at the below solar charger as it is capable of charging 6v batterys (you may also be able to connect the panels you already have). If you wanted to use something other than the arm to move the solar panels, you might get a couple of el cheapo servos and convert them into gearhead motors to pan/tilt the panels.

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=41427