3rd year eletronic engineering project - Page 1
Forum section: electronics / beginners

author: newbie_electron
author_rank: Newbie
timestamp: March 15, 2017, 04:48:37 am
content: Hello guys, the project for the course is out and I am panicking because it worth 50% of overall grade. I know some basic transistor biasing rules, ohms's law and some Kirchhoff's law down. The problem is I know the rule only in the book, but when it comes to designing the circuit to do a specific task, I have no ideas where to start.Please give me a few ideas to start with:Circuit Design Conditions:1. Signal must be Analog based, no microcontrollers will be allowed.2. Total cost must be under $203. Op Amps is preferred however you can use transistors if you up for a challenge.4. Must be your own circuit design idea (LoL)So to all you expert out there, please help!I want to do like a sun tracking system, but I dont know how i can get away with analog based circuit.Thank you all.

author: amspire
author_rank: Super Contributor
timestamp: March 15, 2017, 05:35:18 am
content: If you google search for "analog sun tracking circuit" there is lots of results, particularly if you look at the Images.

author: f5r5e5d
author_rank: Frequent Contributor
timestamp: March 15, 2017, 05:38:56 am
content: a sun tracking demo on the cheap should be possible if you just want to point, not move any largish mass or overcome gravity or wind forcesdriving the motors, building the tracking gimbol assembly is a bit more than EE "analog"the sensor can be a pair of PV diodes and a gnomonconsiderable scope for op amps and transistors in servoing the PV senor output, driving toy DC motors

author: Cupcakus
author_rank: Contributor
timestamp: March 15, 2017, 06:16:57 am
content: Quote from: f5r5e5d on March 15, 2017, 05:38:56 amMotors and gimbals for a < $20 project? How fancy does it have to be? Why not just make a microphone pre-amp/mixer or something? It's just passives and op amps, schematics all over the web for it.

author: f5r5e5d
author_rank: Frequent Contributor
timestamp: March 15, 2017, 07:22:17 am
content: repurposing toy motion mechanisms can be cheap, can give impressive results given today's level of sophistication and price in mass market toysbut audio project are another default to make electronic projects that "do something" that can be appreciated without and oscilloscope

author: amspire
author_rank: Super Contributor
timestamp: March 15, 2017, 07:48:58 am
content: There is also the motors in obsolete CD and DVD drives. The slide that moves the head includes a nice motorized worm drive. Two of those could make a nice N-S and E-W adjustment for a small scale solar tracker.

author: Ian.M
author_rank: Super Contributor
timestamp: March 15, 2017, 07:59:10 am
content: Total cost under $20 would make it very difficult to do a sun tracker.However if you use a cheap RC servo for the mechanism, (e.g.http://www.ebay.com/itm/9G-SG90-Micro-Servo-motor-RC-Robot-Helicopter-Airplane-Control-Car-Boat/272362301472)it may be possible, if you can get the photocells cheap enough.The varying width servo pulse could be generated by an OPAMP circuit or by a CMOS 555 although the latter contains a flipflop so might be too 'digital' for your project supervisor's liking.The first stage would be a bridge with the two photosensors and reference divider feeding an OPAMP that outputs 0V when the tracking is spot on and a varying positive or negative voltage for the direction and speed of movement required. That feeds into an integrator, possibly a full analog PID controller to generate a control voltage representing the sun's position.The control voltage (+ a DC offset) is used to generate the servo pulse by altering the charging time of the timing capacitor in an OPAMP RC oscillator, by clamping the feedback. A diode steering network isolates it from the discharge time so that an average period of 20ms +/- 1ms is maintained.Of course the devil is in the details, but it would be possible to simulate the electronics in LTSPICE to be fairly confident it will work as expected before building it.The other problem is demoing it indoors or on a cloudy day. You'll need to make sure it can track a torch beam in a room , even under normal room lighting.Be aware that you absolutely cannot share the circuit here or on any other public forum until it has been marked and your grade assigned, or ask very detailed questions about your specific implementation as any reputable college uses anti-plagiarism software that searches the web for attempts to pass off someone ele's design as your own. If a search for keywords related to your final project proposal pulls up this topic, you'll loose marks under rule 4. If anyone posts a schematic and you 've used it as a substantial part of your circuit, expect a grade of zero!

author: newbie_electron
author_rank: Newbie
timestamp: March 15, 2017, 09:32:31 am
content: Wow, I did not expect to see so many responses. This gives me a lot of ideas on how to design this thing. It is a challenging project but i will tackle it. I have to come up with a plan and block diagrams tomorrow. I was thinking about making two modules. One is the main unit that holds the solar panels and the other one is the sun sensor unit. They somehow communicates wirelessly. All the main unit does is to listen to a specific frequency (Range within legal limit) sent by the sensor unit and adjust the position accordingly, but on exactly how I done it, i wont share it here. But i'll share after i get it marked.And again thanks everyone. That is such a big help and ideas. I will take everyone ideas and crunch it out into a working project.

author: Ian.M
author_rank: Super Contributor
timestamp: March 15, 2017, 09:34:50 am
content: I doubt you can do the wireless link within your budget - better to plan that as a future upgrade.

author: f5r5e5d
author_rank: Frequent Contributor
timestamp: March 15, 2017, 09:36:47 am
content: "plagiarism" is an odd standard to apply to EE - all engineering is built on copying, extending what works - especially copying known working "function blocks", sticking together textbook, circuit collection book, application note circuitsIn fact I would guess just abstracting a sub circuit for a function you need from a professionally designed product's schematic requires more EE sophistication than I expect of just any 3rd year undergrad

author: newbie_electron
author_rank: Newbie
timestamp: March 15, 2017, 09:46:50 am
content: Transistor and AM transmitter. 😁👍 Envelope detector, you see where i am going? 🤗

author: yashrk
author_rank: Frequent Contributor
timestamp: March 15, 2017, 01:57:45 pm
content: I would suggest you the most obvious choice Dave's own DC dummy load.It can be made totally by using analog components and at the end you will have a good tool handy for your future projects.yashrk.wordpress.com

author: rstofer
author_rank: Super Contributor
timestamp: March 15, 2017, 02:23:04 pm
content: Take a couple of op amps and build up integrators with a 1 second time constant (1 ufd and 1 Mohm). Use two more op amps to form inverters and build a rudimentary analog computer to solve damped harmonic motion. It's a lot easier to do it with op amps than it is with arithmetic.Similar to the attached Matlab implementation except that op amp integrators are inverting and summing is done with the input resistors. So, basically, a lot simpler than the picture.It doesn't get more analog than analog computing!