Thanks, I wasn't planning on sleeping tonight either.
The first schematic with the rectifier makes perfect sense to me, I think. Now, the pot between all of those schematics is the same pot, yes? And V[sub]out[/sub] from the first schematic connects to the source of the top-most power MOSFET? I'm going to assume these are both true. *glances at fixed schematic* Okay, I believe I understand what's wrong with the original in that it would only allow partial discharges.
Now, tell me if I understand this correctly: for that op-amp in the third schematic, at the fully charged state with target/reference voltage X, would
V[sub]+[/sub] = X + V[sub]SD[sub]charging MOSFET[/sub][/sub] and V[sub]-[/sub] = X? So V[sub]out[sub](op-amp)[/sub][/sub] would be V[sub]S+[/sub]? ...and...uh, what would the values of V[sub]S+[/sub] and V[sub]S-[/sub] for the op-amps be?
Also, could you explain in more detail the interactions between the aforementioned op-amp and the MOSFET that share a connection to the reference voltage? Specifically, what happens as the capacitor discharges (when the switch is closed), and does the circuit eventually reach equilibrium (while the switch is still closed)? Part of my confusion probably stems from what the values of V[sub]S+[/sub] and V[sub]S-[/sub] are.
[i][sub]Aside: I don't see a way to control pulse-width and pulse delay with this schematic, but if this is the case, it would seem to be intentional for simplicity's sake. The former is very important for CD welding, as improper timing can overheat the target material. Automating the switch seems the obvious (and perhaps naive) way to accomplish this.[/sub][/i]
[QUOTE=Night-Eagle;33652316]Thanks, I wasn't planning on sleeping tonight either.
The first schematic with the rectifier makes perfect sense to me, I think. Now, the pot between all of those schematics is the same pot, yes? And V[sub]out[/sub] from the first schematic connects to the source of the top-most power MOSFET? I'm going to assume these are both true. *glances at fixed schematic* Okay, I believe I understand what's wrong with the original in that it would only allow partial discharges.
Now, tell me if I understand this correctly: for that op-amp in the third schematic, at the fully charged state with target/reference voltage X, would
V[sub]+[/sub] = X + V[sub]SD[sub]charging MOSFET[/sub][/sub] and V[sub]-[/sub] = X? So V[sub]out[sub](op-amp)[/sub][/sub] would be V[sub]S+[/sub]? ...and...uh, what would the values of V[sub]S+[/sub] and V[sub]S-[/sub] for the op-amps be?
Also, could you explain in more detail the interactions between the aforementioned op-amp and the MOSFET that share a connection to the reference voltage? Specifically, what happens as the capacitor discharges (when the switch is closed), and does the circuit eventually reach equilibrium (while the switch is still closed)? Part of my confusion probably stems from what the values of V[sub]S+[/sub] and V[sub]S-[/sub] are.
[i][sub]Aside: I don't see a way to control pulse-width and pulse delay with this schematic, but if this is the case, it would seem to be intentional for simplicity's sake. The former is very important for CD welding, as improper timing can overheat the target material. Automating the switch seems the obvious (and perhaps naive) way to accomplish this.[/sub][/i][/QUOTE]
Use a micro controller, these guys are always fed up into analog circuit, never seeing the positives to using a micro controller, much more control and easily to upgrade.
Working on a weird little project here.
So every hard drive in existance will make a 5V LED illuminate when it performs a read/write/seek. The only exception is Apple's ProFile hard drive which does the opposite: The LED turns OFF when a read/write/seek is performed + while the drive is initially running its power-on tests.
Inverting the LED will be easy enough (one transistor should do it) but I don't know how to make the LED stay off initially in that first ten or so seconds while the drive is spinning up and getting ready.
[QUOTE=MIPS;33667156]Working on a weird little project here.
So every hard drive in existance will make a 5V LED illuminate when it performs a read/write/seek. The only exception is Apple's ProFile hard drive which does the opposite: The LED turns OFF when a read/write/seek is performed + while the drive is initially running its power-on tests.
Inverting the LED will be easy enough (one transistor should do it) but I don't know how to make the LED stay off initially in that first ten or so seconds while the drive is spinning up and getting ready.[/QUOTE]
Surely a resistor and capacitor will do?
Oh and an opamp
[QUOTE=SubbyV-2;33662800]Use a micro controller, these guys are always fed up into analog circuit, never seeing the positives to using a micro controller, much more control and easily to upgrade.[/QUOTE]
It's about the fun of being able to create the circuit. It's a hobby.
[QUOTE=DrLuke;33669640]It's about the fun of being able to create the circuit. It's a hobby.[/QUOTE]
Are you saying microcontrollers don't have circuitry?
[QUOTE=SubbyV-2;33669684]Are you saying microcontrollers don't have circuitry?[/QUOTE]
I always thought there were tiny little midgets with calculators and did all the work...
But seriously, I think analog electronics are just as much fun as digital electronics.
[QUOTE=SubbyV-2;33669684]Are you saying microcontrollers don't have circuitry?[/QUOTE]
Of course they do, but you didn't make it yourself.
[QUOTE=SubbyV-2;33667307]Surely a resistor and capacitor will do?
Oh and an opamp[/QUOTE]
ddrl46 why rate dumb?
doing something you know isn't fun, learning can be fun.
[QUOTE=SubbyV-2;33662800]Use a micro controller, these guys are always fed up into analog circuit, never seeing the positives to using a micro controller, much more control and easily to upgrade.[/QUOTE]
We do see the positives of using microcontrollers for certain applications (large designs, etc), but often analog circuits can perform the same tasks with greater accuracy, better performance and ultimately less cost, also programming is not everyone's idea of fun I much prefer to 'program' my circuits by design rather than by code, I find it much more efficient and enjoyable.
Also ddrl46 told me the dumb rating was because you never explained the circuit, you clearly have an idea of how to solve the problem but not everyone here understands how to use components such as op-amps, you'll notice that in many of the circuits that I've posted I try to give some explanation to how they function.
Debugging is enough of a pain when you can actually tell what's going on. It's not like you can just run GDB on your MCU and get a backtrace when shit goes down. At least [i]I [/i]can't, I dunno about you guys but I don't have the hardware for ICE or JTAG on my workbench.
Analog is just easier to work with for some things. And you've got physical wires that you can poke and prod when something's not going right.
[QUOTE=DrLuke;33669744]I always thought there were tiny little midgets with calculators and did all the work...
But seriously, I think analog electronics are just as much fun as digital electronics.[/QUOTE]
Agreed, I usually balance my analog circuits and digital circuits. Digital circuits are just a different abstraction than that of analog, so sooner or later its good to learn analog :eng101:
I still see the use of microcontrollers in some cases as cheating.
Then again I'm more a hardware person so of course I'll veer away from having to program shit.
It's not cheating, it's a modern solution to problems.
It gives you direct control over multiple things at once and gives you the ability to process data, which you can't do with analog circuitry. With one analog circuit block, you can usually only perform a single task (i.e. a comperator). But I'm just stating the obvious again.
[QUOTE=DrLuke;33690811]It's not cheating, it's a modern solution to problems.
It gives you direct control over multiple things at once and gives you the ability to process data, which you can't do with analog circuitry. With one analog circuit block, you can usually only perform a single task (i.e. a comperator). But I'm just stating the obvious again.[/QUOTE]
I shy away from microcontrollers because I can't code. :downs:
Put together a small list of parts that I need to buy to build a small Z80 computer with minimal memory and an UART, taking pretty much everything from "Build your own Z80 Computer" or whatever the title of the book was. I'm going to be out of the country for the next 2 weeks though, so I'll order when I get back. Can't wait for it to arrive and start working on it, any tips to debugging the computer?
[QUOTE=MIPS;33690732]I still see the use of microcontrollers in some cases as cheating.
Then again I'm more a hardware person so of course I'll veer away from having to program shit.[/QUOTE]
You don't even know what an RC circuit is...
[QUOTE=SubbyV-2;33698721]You don't even know what an RC circuit is...[/QUOTE]
stop it
[QUOTE=DrLuke;33698936]stop it[/QUOTE]
Not allowed to say using a microcontroller is cheating and that you'd rather use a analog circuit when you don't even know an RC circuit
[QUOTE=MIPS;33667156]Working on a weird little project here.
So every hard drive in existance will make a 5V LED illuminate when it performs a read/write/seek. The only exception is Apple's ProFile hard drive which does the opposite: The LED turns OFF when a read/write/seek is performed + while the drive is initially running its power-on tests.
Inverting the LED will be easy enough (one transistor should do it) but I don't know how to make the LED stay off initially in that first ten or so seconds while the drive is spinning up and getting ready.[/QUOTE]
Here you go
[img]http://i.imgur.com/9xzC8.png[/img]
I assume the hard drive starts up as soon as you push the power button and that the 5V is not
available before that, if it is then I'll have to do it slightly differently.
The delay time is set by adjusting the 100k potentiometer, when the voltage across the capacitor
rises to 2.5V (the reference voltage) the op-amp switches on Q1 which supplies power the the LED.
The LED signal is applied to the base of Q3 which inverts it, so when the signal is low Q2 is turned
on and the LED lights.
[QUOTE=SubbyV-2;33698721]You don't even know what an RC circuit is...[/QUOTE]
Where did he even say he didn't know what a RC circuit is?
Can't you replace both Q3 and Q2 with a single PNP transistor?
[QUOTE=DrLuke;33701499]Can't you replace both Q3 and Q2 with a single PNP transistor?[/QUOTE]
Your quite right, I always end up forgetting about the poor old PNP
[img]http://i.imgur.com/cTHPI.png[/img]
[img]http://i51.tinypic.com/1zdne3n.png[/img]
[QUOTE=ddrl46;33701146]Where did he even say he didn't know what a RC circuit is?[/QUOTE]
Lacking the ability to make a circuit like Chryseus, its implied that he doesn't know how to make a RC circuit
Also Drluke, why rate dumb and wheres your awesome tesla coil?
[QUOTE=SubbyV-2;33705114]Lacking the ability to make a circuit like Chryseus, its implied that he doesn't know how to make a RC circuit[/QUOTE]
Or maybe he just needs help?
Where have you guys learnt about analog circuits and such? You seem to be able to produce advanced schematics in a heartbeat. I'm just getting into it and everything but the very basics is greek to me.
[QUOTE=demoguy08;33705891]Where have you guys learnt about analog circuits and such? You seem to be able to produce advanced schematics in a heartbeat. I'm just getting into it and everything but the very basics is greek to me.[/QUOTE]
I guess books
[editline]13th December 2011[/editline]
At the university I want to go to I will have the chance to specialize in high frequency electronics... it's really crazy shit, because you even have to consider the capacitance and inductance of the copper traces in a pcb to calculate proper frequencies etc...
Good thing we will have a few years before we have to choose a specialization!
[QUOTE=demoguy08;33705891]Where have you guys learnt about analog circuits and such? You seem to be able to produce advanced schematics in a heartbeat. I'm just getting into it and everything but the very basics is greek to me.[/QUOTE]
Books, articles, and more importantly experimenting.
All schematics although they may appear advanced can easily be broken down into smaller circuits that have a specific function, once you learn to recognize what does what things become a lot easier.
[QUOTE=DrLuke;33690811]It's not cheating, it's a modern solution to problems.
It gives you direct control over multiple things at once and gives you the ability to process data, which you can't do with analog circuitry. With one analog circuit block, you can usually only perform a single task (i.e. a comperator). But I'm just stating the obvious again.[/QUOTE]
Still, I'm pleasantly surprised at what Op-Amps can do..Signal Adders, Differentiators, Filters, V-Regs, you name it!
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