Make that C1 and C4.
I doubt that any of these are critical. Ceramic, of film should do fine. If you use ceramic, just use ones that have a voltage rating at least double the expected voltage. Some kinds of ceramic caps have a big drop off of capacitance as the rated voltage is approached.
It is a metal (gate) oxide isolated field effect transistor, N channel (positive gate voltage turn on).
-- John Popelish
Series, but check Mouser and I forget who else I've ordered from.
Could be.
With a Dip meter or inductance meter.
It would just be acting as a volt meter.
Probably. It would lower the turn count but without knowing your application I can't say.
Great. I'll do your electronics and you do my machine work ;)
-- Best Regards, Mike
there
other
It's certainly POSSIBLE, but not without some serious design & construction work. You would need to reproduce the "front end" circuits of a monitor or TV, which take the signals from the video source and modify them so as to properly drive the panel (basically, re-scaling the image format to match that of the panel, convert to the proper drive/timing for the panel in question, etc.). It's not a trivial task, as it involves a good deal more than just taking the panel out of the laptop, feeding it the right voltages, and connecting the video signal to wherever. Again, doable, but not something that you're going to tackle without help if you have no prior experience. And it'll no doubt be a whole lot simpler just to go find a monitor with the appropriate video input.
Gee, it's pretty easy to CLAIM to. :-)
Bob M.
i think it sets the voltage but it looks like theyve got vout and adj pin names transposed in that circuit.
Colin =^.^=
I would be checking the blades !!
-- Regards ........... Rheilly Phoull
Clk in ------------------------------------------- ! NOR -------- Output ! --- ! DBSW !--------! ! ! ----------!D ! ! ------------!Clk ! ! ! Q/ !---------- !--------!
DBSW = debounced switch
You can use the other section of a dual FF to debounce the switch.
-- -- kensmith@rahul.net forging knowledge
Hellow. I'm looking for someone that can provide me with datasheet for TDA1085A. I found datasheet for tda1085c, but they aren't the same. So please help. THX
-- Rok Sitar Slovenia
Digikey sells lots of inductors in the 1000 uHy and above range. The other critical specifications for any inductor are the current rating (both thermal and core saturation may be involved), the self resonant frequency (above which, it looks like a capacitor, instead of an inductor), the DC resistance (affects the heat it produces) and the effective Q (quality factor) at a given frequency, if you are going to use it in a tuned application.
Inductors are one of the few kinds of components you can mak, yourself, that rival the quality of what you can buy. You will need enameled wire of the appropriate size, and ferrite or powdered cores and possibly plastic winding bobbins. The cores and bobbins are what are hard to find. But some are available. For radio frequency inductors, you often need only a form to hold the wire, with air making up the magnetic field path. The whole story is more than I can put in 1 post.
The best way to measure inductance is with a meter made for the purpose, but all sorts of inductance bridge measurements are possible that include a scope or meter as a magnitude and/or phase display that you watch while you null the bridge with known components.
-- John Popelish
Define good. It probably works for some things and is certainly simple ot make. It is not as good as a lab grade adjustable supply that costs a hundred bucks or so.
You should think of this circuit as using the turn on voltage of a transistor as its reference (both for the voltage setpoint and the current limit). Of course this is not a very sharp or temperature stable reference, but it may serve your purposes, which I am not aware of.
-- John Popelish
Yes, you just have to synchronize your on/off with the clock with a FF.
Rene
-- Ing.Buero R.Tschaggelar - http://www.ibrtses.com & commercial newsgroups - http://www.talkto.net
It clamps the output when in constant current mode: if the load wants to be less than 5A, the voltage wants to climb to I * R. R7 is there to prevent that.
Rich
i looked into this for someone i know, and it's possible but not easy. there are custom chips out there to do this, but they are 160 pin surface mount devices which expect to be connected to a microcontroller to handle things like brightness/contrast controls. not a simple project. there is a german company who seem to be selling prebuilt boards to do this -
silicon image and phillips both make chipsets for this.
-- http://www.niftybits.ukfsn.org/ remove 'n-u-l-l' to email me. html mail or attachments will go in the spam bin unless notified with [html] or [attachment] in the subject line.
My PSU need load only at the +12V
it can be done even simpler with a latch,
____ ___ gatesignal --------|D Q|--------| | | | | & |---- CLKout | | +---|___| CLK ---------+----o|LE | | | |____| | +---------------+
-Lasse
If I've read it right and you've a diode feeding each FET gate then I can't even see how they can turn off at all :-). Would not something like a 100ohm resistor be better?. regards john
its even simpler with a latch
____ ___ gatingsignal ---------|D Q|------| | | | | & |---- Gated CLK CLK --------------+--o|LE | +--|___| | |____| | +------------+
Lasse
TAB has published books for the aviation market and electronics hobby market for many years. The electronics books are geared toward beginners and intermediate users, for the most part. They've offered dozens of titles over the years, offering a great variety of hobby projects. Some are rock simple, others a bit more complicated.
One thing I've noticed about TAB books: while the text is almost always quite good, I've never liked the extremely crude drawings they use in the accompanying artwork. In artwork as complicated as an electronic schematic diagram, it is very easy for an artist not knowledgeable about electronics to inadvertently leave out a connection dot or two, or connect components together that shouldn't be.
I'm now in my middle 30s and have tinkered with electronics since my early teens. Looking back through my notes and copies of various books I've used over the years, I can now see where I made some mistakes -- or was led down the wrong path by incorrect information! I have enough experience today to see a great many incorrect schematic diagrams in a lot of TAB's electronics hobby books. I'm wondering if anyone else has noticed this.
My guess is, TAB scrimped on the schematics to hold costs down. But I wonder how many people got burnt out on a potentially rewarding hobby because they could not get a particular circuit to work, no matter how hard they tried... not knowing that the schematic they were following was sabotaged from the get-go! And this is not a magazine where you can read the "Oops!" column next month, this is a book. You seldom see these updated and corrected.
In particular, I remember how aggravated I was trying to get a program to run on a Z-80 microprocessor circuit I built. I eventually was able to figure how that the software program they listed (op-codes and hex equivalents) was not only incorrect, but horribly wrong! In a program with only a dozen lines, I counted three errors! I eventually managed to rewrite the whole thing myself and get it to work. But I could easily have given up. I wonder how many other hobbiests actually did.
Matt J. McCullar, KJ5BA Arlington, TX
separate
attached,
(0.001uF).
the
even
caps.
You are missing the resistor to ground, in parallel to the capacitor. The thing should work by keeping the mosfet completely on, but then limiting the current as Vgs drops. This won't really happen unless there is a path to ground, since the mosfet doesn't pass any current through the gate.
The only thing draining the current circuit is reverse current leakage through the diode. Thats why removing the capacitor caused it to take longer; the diode was leaking away only the capacitance of the MOSFET, not the sum of this and the tiny capacitor you are using.
Check the Vgs curve for your mosfet on the datasheet, and choose the capacitor/resistor so that the gate goes from Vcc to Vgs(th) in 2 seconds. You can do that by using the following formula:
Vgs(th)/Vcc = exp(-2/(R*C))
so
R*C = -2/ln(Vgs(th)/Vcc)
For a Vgs(th) of 4V, and a Vcc of 4V, you have
R*C = -2/ln(4/5) = 9
Thus, you could pick C to be 10uF, and R to be 910k.
Unfortunately, the Vgs(th) in the datasheet is not a very reliable parameter for most power MOSFETs. Thus, you may have to experiment and adjust the values.
Regards, Bob Monsen
I think I was wrong about this circuit. It is alright. What sort of ripple can I expect to get at the output compared to the input, i.e. by how much will the ripple be reduced, and how does that compare with a proper laboratory regulated power supplies ?
p.s. Did you see my other power supply question a few postings before, what's your take on R7, why is it 220R, what does it do ?
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