Electrical Engineering V2

[Van-man]

[QUOTE=LoneWolf_Recon;40573980]Isolating which end of the trimpot adjusts Ton & Toff, by controlling flow (Not the best way to do PWM for a 555, but its an easy way)[/QUOTE]

Shit's working, tested it on a breadboard.

[URL="http://en.wikipedia.org/wiki/KISS_principle"]K.I.S.S.[/URL]

[alexaz]

Has anyone ever tried spraying photoresist onto a board? I'v sprayed one board successfully some time before, but today i have tried 10 boards and all of them failed. Mainly, the photoresist over time just coalesces into one big drip. If i heat it, the coalescence accelerates. It seems like the board is hydrophobic. I'm using Positiv20 and beforehand i sand the oxides off with a light sandpaper and then clean it with water/acetone/isopropyl ( all at once too ) but the shit just won't work.

EDIT: nvm, cleaned a board with a water jet and it seems to work wonders. water > solvents

[Cakebatyr]

[t]http://i.imgur.com/a5kHj4I.jpg[/t]

This would be a lot more impressive if I hadn't forgotten my USB-A/B cable and had it hooked up to my software :(

[Chryseus]

[QUOTE=Cakebatyr;40609520]
This would be a lot more impressive if I hadn't forgotten my USB-A/B cable and had it hooked up to my software :([/QUOTE]

Connecting up two boards is impressive ?
Dare I ask what it's meant to do ?
:downs:

Sorry if I sound like an ass, it's my job to convert you to the wonderful world of analog.
Resistance is futile.

[Cakebatyr]

[QUOTE=Chryseus;40609831]Connecting up two boards is impressive ?
Dare I ask what it's meant to do ?
:downs:

Sorry if I sound like an ass, it's my job to convert you to the wonderful world of analog.
Resistance is futile.[/QUOTE]

Well, I would argue that connecting two boards together and powering them is more impressive than just simply connecting two unpowered boards together.

[MatheusMCardoso]

[QUOTE=Cakebatyr;40609520][t]http://i.imgur.com/a5kHj4I.jpg[/t]

This would be a lot more impressive if I hadn't forgotten my USB-A/B cable and had it hooked up to my software :([/QUOTE]

Your keyboard needs some serious cleaning.

[Agent766]

[QUOTE=MatheusMCardoso;40610886]Your keyboard needs some serious cleaning.[/QUOTE]

Seriously, there's microcontrollers all over it. You pig.

[Van-man]

[QUOTE=Chryseus;40609831]the wonderful world of analog.[/QUOTE]

Filled with [B]NOISENOISENOISENOISENOISE[/B]

[DrLuckyLuke]

The digital world is so much nicer.

[Fuxed]

[QUOTE=Chryseus;40609831]
Resistance is futile.[/QUOTE]

Which makes conductance a worthy effort!

I really, really want an FPAA on that note.

[Chryseus]

[QUOTE=DrLuckyLuke;40615653]The digital world is so much nicer.[/QUOTE]

But not nearly as fun.

[alexaz]

[QUOTE=MatheusMCardoso;40610886]Your keyboard needs some serious cleaning.[/QUOTE]

You consider that dirty?
*looks at his keyboard*

[Van-man]

[QUOTE=Chryseus;40615816]But not nearly as fun.[/QUOTE]

Not everyone is into sadomasochism.

[DrLuckyLuke]

[QUOTE=Chryseus;40615816]But not nearly as fun.[/QUOTE]

Well, combining both probably is the best fun you can have

[LoneWolf_Recon]

But its fun to balance the two, analog and digital systems.

Ergo Embedded Systems baby.

[DrLuckyLuke]

the Cypress PSoC does that in a wonderful way. It has internally configurable analog paths, so you can feed two signals into an internal opamp and map the output to any analog output-pin you want, or process it further internally (another opamp, adc, comperator)

[ben1066]

[QUOTE=thomasfn;40571702]Finally got round to playing with my FPGA. Learning verilog and how to use ISE.

Witness the innovation!

module main(
    in,
    out
    );
	 
output out;
input in;

assign out = in;

endmodule

I call it the InOut 4000[/QUOTE]

I should really do something with my FPGA board but HDL is so different to anything else.

[BuG]

[QUOTE=ben1066;40618278]I should really do something with my FPGA board but HDL is so different to anything else.[/QUOTE]

I personally prefer VHDL over Verilog.

That being said, I prefer not working with FPGA's at all. :v

[ben1066]

[QUOTE=BuG;40633158]I personally prefer VHDL over Verilog.

That being said, I prefer not working with FPGA's at all. :v[/QUOTE]

That's the issue I've got, I like the concept, but it seems counter productive since what I can do in an FPGA, I can do in C 10x faster.

[LoneWolf_Recon]

Quick question, I'm selecting inductors for a boost converter and trying to minimize losses.

Would a toroidal inductor be more efficient considering it constrains all of its magnetic flux within the core instead of an axial inductor?

[Fuxed]

[QUOTE=ben1066;40642629]That's the issue I've got, I like the concept, but it seems counter productive since what I can do in an FPGA, I can do in C 10x faster.[/QUOTE]

Ah, but then we have glorious concurrent end-results if you do it right. Plus there's nothing to stop you throwing in a soft-core and doing large parts with C with HDL backend and custom peripherals. FPGAs are a great thing in their own right and totally worth the effort to learn the intricacies of.

[DrLuckyLuke]

[QUOTE=LoneWolf_Recon;40643343]Quick question, I'm selecting inductors for a boost converter and trying to minimize losses.

Would a toroidal inductor be more efficient considering it constrains all of its magnetic flux within the core instead of an axial inductor?[/QUOTE]

Check out the datasheet, they often suggest inductors.
A toroid probably wouldn't really be that much more effective.

[Van-man]

[QUOTE=DrLuckyLuke;40644293]Check out the datasheet, they often suggest inductors.
A toroid probably wouldn't really be that much more effective.[/QUOTE]

Since a toroid based one has minimal magnetic leak compared to a "pole" based inductor it should be more effective.
Although winding a itty bitty one wouldn't be worth the effort compared to the power loss.

[editline]14th May 2013[/editline]

Dug around a bit on the Toroidal versus "log" style inductors thing and found this:
[URL]http://www.societyofrobots.com/robotforum/index.php?topic=15591.0[/URL]
Seems to confirm that Torodial based inductors ARE indeed more effective, [B]BUT[/B] only when they're carefully made for the exact circuit.
Also there's also a third type nicknamed [I]pot core
[/I][t]http://filesmelt.com/dl/Dexter_Magnetics_Pot_Core_10.jpg[/t]

[Gulen]

I'm going to be showing off electrical engineering to about 300 people today. Wish me luck!

[ben1066]

Toying around with the idea of making a digitally controlled power supply, with both constant voltage and constant current. The former is easy with just an opamp and a transistor, the latter a little more complex, at least, I have a lesser understanding of it. I'm not sure how accurate circuit lab is, but should the following work? Vset being 1/0th the current limit, eg, 1.0A so 0.1V . R4 is just a replacement for my load.
[url=https://www.circuitlab.com/circuit/3ar8w6/op-amp-constant-current/][img]https://www.circuitlab.com/circuit/3ar8w6/screenshot/540x405/[/img][/url]

[Chryseus]

[QUOTE=ben1066;40651592]Toying around with the idea of making a digitally controlled power supply, with both constant voltage and constant current. The former is easy with just an opamp and a transistor, the latter a little more complex, at least, I have a lesser understanding of it. I'm not sure how accurate circuit lab is, but should the following work? Vset being 1/0th the current limit, eg, 1.0A so 0.1V . R4 is just a replacement for my load.
[url=https://www.circuitlab.com/circuit/3ar8w6/op-amp-constant-current/][img]https://www.circuitlab.com/circuit/3ar8w6/screenshot/540x405/[/img][/url][/QUOTE]

I'll have a closer looking in a minute.
By the way you can use labels in circuit lab as a DC voltage source, just type something like +5V, -5V, +24V, etc.

Ok the problem with that circuit is you cannot set the voltage and current at the same time using a single op-amp as far as I'm aware.
Here is a two op-amp circuit that will switch in to constant current mode automatically.

[t]http://u.cubeupload.com/Chryseus/MZnXOw.png[/t]
[t]http://u.cubeupload.com/Chryseus/vvueql.png[/t]

[ben1066]

Sorry if I didn't make it clear, but that is intended to just be the constant current supply, the constant voltage supply would replace the 10V supply on the left, that's simpler with just an opamp, a bjt and a few resistors to set gain. The Vset should really be Iset.

[thomasfn]

I'd like to get my hands on one of [url=http://www.tabula.com/products/abax_22nm.php]these[/url]. Probably a tad too expensive for a student enthusiast though.

[Chryseus]

[QUOTE=ben1066;40663012]Sorry if I didn't make it clear, but that is intended to just be the constant current supply, the constant voltage supply would replace the 10V supply on the left, that's simpler with just an opamp, a bjt and a few resistors to set gain. The Vset should really be Iset.[/QUOTE]

In that case your circuit should work fine as a constant current source as long as the shunt resistor is not too large or too small for your desired current range.

[chaz13]

I want to mess about with an op-amp to make a super simple audio/signal amplifier..

If I want volume/gain control and I'm using a non-inverting op amp configuration, is it better to use a pot for the feedback resistor, or to make a voltage divider after the op-amp?

Using it as the feedback resistor may be too sensitive, and also non-linear, but uses less parts - so it's probably better to have a potential divider after the op-amp, right? But then you lose half the output voltage.

Basically, is A or B better:

[IMG]http://i41.tinypic.com/ormjhw.png[/IMG]

(ignore the resistances, didn't bother changing them)