Electrical Engineering V2 - Developers

The battery may just remain charging at a constant rate as USB ports, typically, only supply 500mA. Unless it's explicitly stated, you may not see that much an improvement with more panels.

So those voltmeters came in and as expected, they were NOT the dimensions specified. :v:

[QUOTE=pentium;45689292]So those voltmeters came in and as expected, they were NOT the dimensions specified. :v:[/QUOTE] 53 milli-inches?

[QUOTE=pentium;45689292]So those voltmeters came in and as expected, they were NOT the dimensions specified. :v:[/QUOTE] Tell us the differences... I am curious :p

[QUOTE=quincy18;45696816]Tell us the differences... I am curious :p[/QUOTE] Pretty sure they advertised them as being 96mm square but he got 72mm square (which is what he wanted so no worries).

Yeah, they were advertised as 96mmx96mm but from the picture they were obviously 72mmx72mm. So we gambled that the picture was right and the description was wrong and we were right. :v: Also, I reorg'd the shelf to fit most of that new gear. [IMG]http://i11.photobucket.com/albums/a166/ballsandy/CGS_0823.jpg[/IMG] Can't find a proper home for the recorder though. [IMG]http://i11.photobucket.com/albums/a166/ballsandy/CGS_0831.jpg[/IMG]

Dude your shelf is bending. Completely unrelated and maybe stupid question: Is there some kind of rubber-band like component that measurably increases in resistance the more it gets stretched? Edit: [URL="http://www.adafruit.com/products/519"]Apparently, there is.[/URL]

That's the lens. The table is not bending that badly.

Added bluetooth to an old pair of portable speakers: [t]http://i.imgur.com/7LvlGkI.jpg[/t] Broke a couple things in the process of putting it back together, though for the most part it works! I just have to keep a 3.5mm cable plugged in all the time, since I guess it powers down the amp to save power when the line-in is disconnected.

How'd you do it? I've been thinking of doing something like that for a while, but I have no idea where to start.

[img]http://i592.photobucket.com/albums/tt8/donreid1939/Jul%202014%20-4/SDIM0513_zps62d1ad3b.jpg[/img] New High Voltage probe~ Yay :)

[QUOTE=Gulen;45715697]How'd you do it? I've been thinking of doing something like that for a while, but I have no idea where to start.[/QUOTE] I bought a cheap bluetooth receiver dongle from eBay, looked up the chips on the speaker board to see if they used 5v, found the 5v line, removed the usb connector on the dongle and hooked it up directly to the 5v line I found, then soldered on wires to the audio connections.

Huh. Got a link to that dongle? And wouldn't it be possible to trick the speakers into thinking the line-in is connected?

Soooo, I'm a noob at Electric-stuff but I want to do sth. I got a 5m RGB LED Strip powered by 12 Volt. The connectors look sth like this: [t]http://i.imgur.com/y7vUIyM.png[/t] 1 for +12, 3 for R G and B To control it, I want to hook it up to my PI and then control it via the PI. So I already bought an Adapter for the 12 Volt power cable and some N-LogL-MOSFET 55V 30A 68W (got them for free) but I guess they are the wrong ones... (Can someone explain what they do for noobs?) I tried following circuit but I wasnt able to light it: [t]http://mitchtech.net/wp-content/uploads/2013/01/raspi_rgb_led-300x194.png[/t] Someone can help me and give me tips? Or what I need for it?

You sure that those mosfets don't have too high a threshold voltage? Meaning, the PI or the power supply don't have high enough a voltage to trigger the mosfet? Oh, and you need ground somewhere, or else current wont flow.

[QUOTE=Gulen;45717179]Huh. Got a link to that dongle? And wouldn't it be possible to trick the speakers into thinking the line-in is connected?[/QUOTE] [url]http://www.ebay.ca/itm/131211866639?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649[/url] My speakers have this kind of 3.5mm jack: [IMG]http://i.imgur.com/SWRRMVH.jpg[/IMG] When there isn't anything plugged in, the tip and ring terminals short to the pin next to them. I figure if i could desolder the jack and clip those legs, it would work just fine. Though I wasn't having any luck desoldering them and it was about 1:30AM at that point and I just wanted to finish.

[QUOTE=Gulen;45717341]You sure that those mosfets don't have too high a threshold voltage? Meaning, the PI or the power supply don't have high enough a voltage to trigger the mosfet? Oh, and you need ground somewhere, or else current wont flow.[/QUOTE] So, If I understood mosfets correctly: If you put enough power onto the gate, it will trigger and voltage will go from left to right? What would be suitable for 12V then? And also, can I control how much voltage can go through it? e.g for dimming the light

I'd just like to say a big thank you to ddrl46. He helped me on Steam with some very basic questions I had and has gone on to provide me with some very useful tips and support. What a great person <3

[QUOTE=johnnyaka;45719065]So, If I understood mosfets correctly: If you put enough power onto the gate, it will trigger and voltage will go from left to right? What would be suitable for 12V then? And also, can I control how much voltage can go through it? e.g for dimming the light[/QUOTE] Alright, mosfets are kinda difficult to explain. I'm assuming you know how leverage works: Let's say you have a very long piece of wood, that sits on a point. On one side, you have something heavy (your power source), on the other, there's nothing, the piece of wood is just so long on that side, that the load stays up. Now, on the side that's far down, is you. You want the load down, but physics want it up. So what do you do? Well, you can push the side you're on upwards. Now you're a control voltage. You control how far down the load is (how much voltage is going through to the output) So, the more voltage you shoot on the control, the more voltage can flow from the input to the output, with very little current draw from the controller (the Pi) The mosfet acts as a valve of sorts, controlled by the control voltage. [editline]17th August 2014[/editline] Oh, and just because your power source is 12V, doesn't mean the Pi is.

[IMG]http://i.imgur.com/0MUVSZt.png?1[/IMG] Altera please get your shit together. That's not my internet connection, that's their crappy servers.

[QUOTE=Gulen;45719744]Alright, mosfets are kinda difficult to explain. I'm assuming you know how leverage works: Let's say you have a very long piece of wood, that sits on a point. On one side, you have something heavy (your power source), on the other, there's nothing, the piece of wood is just so long on that side, that the load stays up. Now, on the side that's far down, is you. You want the load down, but physics want it up. So what do you do? Well, you can push the side you're on upwards. Now you're a control voltage. You control how far down the load is (how much voltage is going through to the output) So, the more voltage you shoot on the control, the more voltage can flow from the input to the output, with very little current draw from the controller (the Pi) The mosfet acts as a valve of sorts, controlled by the control voltage. [editline]17th August 2014[/editline] Oh, and just because your power source is 12V, doesn't mean the Pi is.[/QUOTE] Yuck I hate analogies. A MOSFET is essentially a voltage controlled current source, the gate to source voltage programs the current that can flow through the drain and source terminal, another way to think of this is the conductance (resistance) of the drain to source terminal is controlled by the voltage applied between the gate to source terminal. MOSFETs come in two main types (4 actually but not important) N and P, this refers to the type of semiconductor used to make the drain to source, the important thing is that you use N and P type slightly differently, a N channel MOSFET (the most common) requires a positive voltage between the gate to source while a P channel requires a negative voltage between the gate to source for the channel to conduct, voltage is of course relative between two points so you don't actually need a 'negative' supply, to turn a P channel on you can have the source terminal a higher voltage than the gate. Each MOSFET part (as well as some variation between individual MOSFETs) has a different threshold voltage, this is the gate to source voltage you need to exceed if you want it to act like a semi-ideal switch, this varies between 1V to 10V. For your specific application I'm assuming your LED strip is common anode and that it has no built in controller, for this you need to connect the drain of each MOSFET to the R, G and B pins, the common to the positive supply, the source to ground. If the LED strip had its own resistors you don't need anything else, if it does not you will need a resistor in the drain of each MOSFET to limit the current to a safe value. (given in the datasheet for the strip) Since you want to vary the brightness of each channel you will need to vary the voltage applied to the gate or more easily use PWM (pulse width modulation), I don't have a RPI so I can't tell you how to do that, maybe someone else can help there.

100W LED [url]http://www.dx.com/p/100w-9000lm-3050k-warm-white-light-10-x-10-led-module-33-35v-169052#.U_I-7_mSxct[/url] Hello, I want to do driver for this LED, so 100W 33-35V. I want to control this LED with Raspberry PI. What should I do? My intent: I want to do wake-up light (simulate sun every morning, fade in (0% brightness -> 100%), for 15 minutes. Then shut down.

A 100w led certainly will simulate sunlight. Just not sure being on the suns surface is very pleasant for a morning experience. Edit: 100w leds are used as floodlights to light up entire driveways. Try 10w.

[QUOTE=Fourier;45728446]100W LED [url]http://www.dx.com/p/100w-9000lm-3050k-warm-white-light-10-x-10-led-module-33-35v-169052#.U_I-7_mSxct[/url] Hello, I want to do driver for this LED, so 100W 33-35V. I want to control this LED with Raspberry PI. What should I do? My intent: I want to do wake-up light (simulate sun every morning, fade in (0% brightness -> 100%), for 15 minutes. Then shut down.[/QUOTE] You do realize that this produces the same amount of light as a 3000W lightbulb would, do you?

[QUOTE=Fourier;45728446]100W LED [url]http://www.dx.com/p/100w-9000lm-3050k-warm-white-light-10-x-10-led-module-33-35v-169052#.U_I-7_mSxct[/url] Hello, I want to do driver for this LED, so 100W 33-35V. I want to control this LED with Raspberry PI. What should I do? My intent: I want to do wake-up light (simulate sun every morning, fade in (0% brightness -> 100%), for 15 minutes. Then shut down.[/QUOTE] I would use a PWM output of the PI (if it has one or you could do it with an arduino.) You would then put it to a decent sized MOSFET (N-Channel) Then you put an inductor with it and some diodes etc to smooth the current from chopped DC to an analog output, then put that to the LED. Somthing like that anyway, i recently did a motor controller.

[QUOTE=nuttyboffin;45728577]I would use a PWM output of the PI (if it has one or you could do it with an arduino.) You would then put it to a decent sized MOSFET (N-Channel) Then you put an inductor with it and some diodes etc to smooth the current from chopped DC to an analog output, then put that to the LED. Somthing like that anyway, i recently did a motor controller.[/QUOTE] I'd use a dedicated microcontroller or pwm IC for that.

[QUOTE=chipset;45728547]A 100w led certainly will simulate sunlight. Just not sure being on the suns surface is very pleasant for a morning experience. Edit: 100w leds are used as floodlights to light up entire driveways. Try 10w.[/QUOTE] I don't intend to use it to 100% I just don't want to be limited by 10w LED. I need 10,000 Lumen FYI [editline]18th August 2014[/editline] [QUOTE=DrDevil;45728597]I'd use a dedicated microcontroller or pwm IC for that.[/QUOTE] Nah Raspberry PI has cool PWM, I used it for LEDs already and it's ok :)

[QUOTE=Fourier;45728641]I don't intend to use it to 100% I just don't want to be limited by 10w LED. I need 10,000 Lumen FYI[/QUOTE] Why? 10000 lumen is an enormous amount of light for this purpose. A high wattage ceiling light bulb is 1000 lumen and it lights up an entire room.

[QUOTE=DrDevil;45728548]You do realize that this produces the same amount of light as a 3000W lightbulb would, do you?[/QUOTE] W-w-w-what, now I really need to try this. I won't put it so that it directly shines into me, no way, but I would put it across the room :). [editline]18th August 2014[/editline] [QUOTE=chipset;45728695]Why? 10000 lumen is an enormous amount of light for this purpose. A high wattage ceiling light bulb is 1000 lumen and it lights up an entire room.[/QUOTE] Uh oh sorry, I meant 10,000 [b]lux[/b]. [editline]18th August 2014[/editline] [QUOTE=nuttyboffin;45728577]I would use a PWM output of the PI (if it has one or you could do it with an arduino.) You would then put it to a decent sized MOSFET (N-Channel) Then you put an inductor with it and some diodes etc to smooth the current from chopped DC to an analog output, then put that to the LED. Somthing like that anyway, i recently did a motor controller.[/QUOTE] Ok got that, problem arises because I will need to drive this big MOSFET with another transistor, and making custom power supply for LED. Hmm, maybe I could just buy the driver somewhere I guess. [editline]18th August 2014[/editline] Here, the driver.. I guess it is exactly for this job :) [url]http://www.dx.com/p/3-0a-100w-power-constant-current-source-led-driver-85-265v-47306#.U_JF3fmSxcs[/url] Ok, this driver has constant current, which means I only need to switch this current with MOSFET, no?

Just keep in mind that this WILL blind you if you directly look at it. You should wear appropriate eye protection when you work with it, and design your PWM controller to fail into the off-state at all times.