[Suggestions] What is wrong with this schematic? - Page 1
Forum section: electronics / beginners

author: WaRc3L
author_rank: Contributor
timestamp: July 30, 2015, 02:12:05 pm
content: Hello everybody,I am newbie into design of PCB and I need your help for a suggestions about this schematic. It's a simple triangular-wave generator with a potentiometer to modify the frequency of the signal.Can I do it better?, what's seen in the schematic that "cries" your eyes?Thanks for all, and sorry for my english.pD: Do you know any tutorials or suggestions on Internet to pass the schematic into a board-design PCB?, I have seen the BenHeckShow tutorial and Jeremy Blunm on youtube, but it's not enough for me...Regards,Marcel

author: McBryce
author_rank: Super Contributor
timestamp: July 30, 2015, 02:18:50 pm
content: The first thing that's obvious is that it's extremely difficult to read at a glance. did you make the 741 symbol yourself? Eagle already has a 741 symbol in it's library. The circuit is much easier to understand if you use the standard op-amp type symbol (see attachment).McBryce.

author: WaRc3L
author_rank: Contributor
timestamp: July 30, 2015, 02:26:13 pm
content: Quote from: McBryce on July 30, 2015, 02:18:50 pmYeah, it's obvious. I found the symbol into ST Microelectronics, I don't remember why. Thanks!!!.Any other suggestions?Regards,Marcel

author: McBryce
author_rank: Super Contributor
timestamp: July 30, 2015, 02:41:36 pm
content: The green dots on the component pins aren't necessary unless there is more than one wire (net) going to the pin. The dots are usually just for joining two wires together. A single wire going to a pin is automatically connected. It's not wrong how you have it, just more work than is needed.McBryce.

author: WaRc3L
author_rank: Contributor
timestamp: July 30, 2015, 06:15:54 pm
content: Perfect!!!, thanks a lotRegards,Marcel

author: Neilm
author_rank: Super Contributor
timestamp: July 30, 2015, 07:02:57 pm
content: A personal preference of mine - if two wires are crossing and are connected, I don't have them in the form of a cross as you have for your TRI port, but will offset them to form 2 T intersections. This means that I can tell at a glance that when one wire is going over another they are not connected rather than having to look. . It also means that if I see dot in this situation, I know to have a good look to check they should be connected.

author: codeboy2k
author_rank: Super Contributor
timestamp: July 30, 2015, 07:37:27 pm
content: Quote from: Neilm on July 30, 2015, 07:02:57 pmYes, this is very important, and something I always do too. Crossed wires never connect, and connections are only made using 'T' junctions, never '+' like that.This way you always know when something is or is not connected -->> "T" junctions ALWAYS connect. "+" junctions NEVER connect.

author: c4757p
author_rank: Super Contributor
timestamp: July 30, 2015, 07:39:26 pm
content: Multiple standards require this, and for a reason.

author: WaRc3L
author_rank: Contributor
timestamp: July 31, 2015, 03:32:02 pm
content: Quote from: Neilm on July 30, 2015, 07:02:57 pmWow, thanks Neilm and codeboy2k!!.With all about your suggestions, I made this schematic. Is it better?.And, to reuse the post, I designed this PCB board with the Autorouter of Eagle. What do you think?, Is it really finished?.I remember that I am newbie with the designs of PCB...Regards,Marcel

author: milow
author_rank: Contributor
timestamp: July 31, 2015, 06:16:10 pm
content: The triangle wave is at the output of U1. Right now, you would get a linear combination of the triangle wave and the rectangular wave.

author: WaRc3L
author_rank: Contributor
timestamp: July 31, 2015, 07:55:37 pm
content: Quote from: milow on July 31, 2015, 06:16:10 pmThanks for the annotation!

author: Zero999
author_rank: Super Contributor
timestamp: July 31, 2015, 08:59:54 pm
content: Do you want to vary the frequency of the triangle wave, without changing its amplitude? If so then you need to make R1 the potentiometer and leave R3 fixed.The 741 is only suitable for low frequencies. You won't get a very good squarewave above a couple of kHz. I haven't done any calculations so don't know what frequency it'll oscillate at.

author: Hideki
author_rank: Frequent Contributor
timestamp: July 31, 2015, 10:34:37 pm
content: Quote from: WaRc3L on July 31, 2015, 03:32:02 pmNo. While it is connected up according to the schematic, it does looks like what you get when you let a beginner use the autorouter. The only reason to use an autorouter if you're a beginner is to try it out and learn some of the possible ways that traces can be connected. Once you get better at figuring that out you should do it manually... every time, every single time, always. After you get really good at it (maybe some years later) you can consider looking at autorouters again.The components are placed almost at random with large areas of unused space instead of grouping the components in any way. Strange connections all over the place. When you have that few components you really should try keeping all the connections on one side. Bottom if through hole and top if surface mounted. 2 layer prototype boards cost the same, so it's not that you HAVE to. It's just good style. Especially when you're learning how to do it.