Somehow I've managed to go a fairly long time without needing a bench supply. All I use is an ATX 12V supply which has met my needs until last night when I badly needed ~3.75V. After taping 3 AA batteries together and draining them in about a minute I said fuck this, and slapped this lil piece of shit together:
[thumb]http://i.imgur.com/jovlGWM.jpg[/thumb]
There's a poor little BD437 NPN BJT being used as a current buffer, dissipating somewhere around 30W or so. Without the fan the heatsink was hot enough to burn me. And the small guage jumper wires acted nicely as current limiters.
I actually have a dual benchsupply project I just started working on though. +-50V @ 5A, +-12V @ 10A. Adjustable voltage and current, OCP, all that fun stuff.
[QUOTE=ddrl46;45221773]Woop, finished my network analyzer detector adapters.
Just decided to kinda copy the design of the original detector adapters (HP 11664C) for my network analyzer since those cost way too much for what they are.
[url=http://i.imgur.com/hmRNKRV.jpg][img]http://i.imgur.com/hmRNKRVl.jpg[/img][/url]
[/QUOTE]
Dylan Packard?
Wait a minute.....
Ordered me some stuff to make a few IR Jammers.
There's a guy at work that keeps messing with the radio remote, and since ripping the batteries out just makes him get new ones, I decided to just jam the damn thing. :v:
Was intending to build a weather station, and am still waiting for the sensors to arrive. Anyone have experience with the NRF24L01+ wireless transcievers? I was wondering how the many to one networking works, because if it's quite easy to work with then I was thinking that maybe I could go further than a weather station, and have multiple nodes in different rooms. The sensors that I've planned so far are the DHT22 for humidity and temperature and the BMP180 for pressure and temperature, possibly the TSL2561 for light levels. The first too still make sense in an interior environment, and the latter does to an extent. A weather station would ideally have a wind vane and anemometer too, but I'm not sure how I'd implement either of those. Also bought myself a small FX2 based logic analyser, I did intend to use sigrok's software but unfortunately it can't seem to keep up with the higher data rates yet. It does work under Saleae's software though, even if I feel terrible for using it.
Just letting you lot know im selling some capacitors in order to buy some parts for a monster IGBT, opto-isolated full bridge power supply to drive X-Ray transformers:
[url]http://4hv.org/e107_plugins/forum/forum_viewtopic.php?164323.0[/url]
TS;SDR: (Too Short, Still Didn't Read)
I brought too much stuff and i need to sell it to buy more other stuff.
[QUOTE=nuttyboffin;45247662]Just letting you lot know im selling some capacitors in order to buy some parts for a monster IGBT, opto-isolated full bridge power supply to drive X-Ray transformers:
[url]http://4hv.org/e107_plugins/forum/forum_viewtopic.php?164323.0[/url]
TS;SDR: (Too Short, Still Didn't Read)
I brought too much stuff and i need to sell it to buy more other stuff.[/QUOTE]
How much is shipping on these?
[QUOTE=Subby;45170577]I thought i was buying a 100W LED Module, ended up being 33W.
I've bought one off DX that says 100W, hopefully it comes soon.[/QUOTE]
It came, it's 100W; fucking bright as shit.
Can anyone recommend a good place to purchase 18650s?
[QUOTE=ben1066;45251702]How much is shipping on these?[/QUOTE]
only around £5 for 1-2 kg and £8 for 3-5 or there abouts, its not much.
I'm a little tempted to buy a capacitor, just not sure how much use I'd get from it to spend £4 (yes i'm cheap)
you should totally buy loads of them and make a powerful coil gun. i could even give you the design for a driver to charge them up! ;D
[QUOTE=Subby;45252141]It came, it's 100W; fucking bright as shit.
Can anyone recommend a good place to purchase 18650s?[/QUOTE]
Dealextreme
[QUOTE=nuttyboffin;45254568]you should totally buy loads of them and make a powerful coil gun. i could even give you the design for a driver to charge them up! ;D[/QUOTE]
I would if I could afford it! I really would.
[QUOTE=ddrl46;45255266]Obligatory
[img]http://puu.sh/2aiqV[/img]
[img]http://puu.sh/2air8[/img][/QUOTE]
That shouldn't be legal, aha
[editline]30th June 2014[/editline]
[QUOTE=Leestons;45255275]I would if I could afford it! I really would.[/QUOTE]
How much monies you got? i will sort it out so i use it all :)
[QUOTE=nuttyboffin;45255332]That shouldn't be legal, aha
[/QUOTE]
It isn't. But China just doesn't give a fuck.
[QUOTE=DrDevil;45255440]It isn't. But China just doesn't give a fuck.[/QUOTE]
Some of them are just smaller batteries inside the bigger case, packed with flour.[IMG]http://www.powerstream.com/z/flour-battery.jpg[/IMG]
Ultrafire battery, taken from the DX forums for that listing.
[img]http://i.imgur.com/aPGyA.jpg[/img]
Well, you guys sure are glass half empty guys.
Why don't you see it this way instead: Now you can bake roughly 1.3 cookies per battery!
[QUOTE=DrDevil;45256059]Well, you guys sure are glass half empty guys.
Why don't you see it this way instead: Now you can bake roughly 1.3 cookies per battery![/QUOTE]
With Chinese flour?
[QUOTE=Tamschi;45256101]With Chinese flour?[/QUOTE]
You're right, it's probably fake flour.
anthrax?
[editline]1st July 2014[/editline]
gg china
At least now you get to die quickly because of the cookies you made; rather than burn slowly in the fire caused by the batteries.
Does anybody know of a good resource about solder stencils? I'm specifically looking at determining the exact aperture size I need for a pad without having to resort to expensive trial and error.
I've found that most IC manufacturers offer informative PDFs about their packages, including a recommended footprint and paste layout. Is this "the" way to determine aperture size properly?
I wish people would stop bidding on items with 5 days left of the auction and hiking up the price.
I bought a tektronix 2213 oscilloscope to help debug my power supply circuit among other things.
As it turns out the problem wasn't with the 338 but with the path from the VOUT pin to the ADJ pin. When a large >1A current was flowing the small voltage drop of about 50 milivolts over the crappy breadboard connectors was being magnified x12 and showing up in the output as a voltage drop when loads were applied. Mystery solved. Don't put high currents through a breadboard.
Here's a question for you guys:
Say we have a half-wave rectifier, so our output current/voltage waveform looks like this:
[img]http://upload.wikimedia.org/wikipedia/commons/5/51/Waveform_halfwave_rectifier.png[/img]
Through integration, we can find two different values which represent this waveform. That is, the RMS and average/DC equivalent.
The RMS voltage of that waveform is Vp/2
The average/dc voltage of it is Vp/pi
This is confusing to me since I was under the impression the RMS value was already the DC-equivalent value. So if I were to calculate DC power through the load, would I do it with [Vp Ip] / 4 or [Vp Ip] / pi^2
The RMS is the average amplitude of the AC+DC part.
For the second formula you're naming two different things. The numerical average doesn't truly represent the average energy of the waveform, while the DC-component of the waveform is really just like a constant offset that gets added onto the AC-component (think of a waveform like sin(x) + 1. The DC-component would be 1.)
[QUOTE=DrDevil;45296703]The RMS is the average amplitude of the AC+DC part.
For the second formula you're naming two different things. The numerical average doesn't truly represent the average energy of the waveform, while the DC-component of the waveform is really just like a constant offset that gets added onto the AC-component (think of a waveform like sin(x) + 1. The DC-component would be 1.)[/QUOTE]
But there is no AC part here? It's rectified AC therefore it's DC, right? So the power you calculate would be DC power using the RMS values, and the average values are just...useless?
But then I see people using the average values to calculate the "DC power" through a resistor...
Example: 170Vp is the source, 100ohm load.
Vrms = 85V
Irms = .85A
P = 72W
Vdc = 54V
Idc = .54A
Pdc = 29W
I know the top one is correct but whats the point of the second one? Is there like an AC power I can find as well?
[editline]4th July 2014[/editline]
There is an AC power...65V @ .65mA = 43W. 29+43 = 72W. I sort of got that through trial and error. I'm just not seeing how that waveform can have AC and DC components in it.
I think I figured it out. I had no idea you could separate the total power into an AC and DC portion for non-symmetrical waveforms (over the x-axis). Makes sense in hindsight.
As you can see, the value of the waveform changes over time, so you have an AC part, even if all of the voltage is positive.
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