Electronics and Embedded Programming V3

[Ddrl46]

[QUOTE=chipset;36834551]Those copper clad PCD's are for etching, unless you know how to etch pcb's and have etching supplies you probably want to build up your projects after breadboarding on these:

[url]http://www.dealextreme.com/p/prototype-universal-printed-circuit-board-breadboards-brown-10-pack-132929?item=14[/url]
[url]http://www.dealextreme.com/p/prototype-universal-printed-circuit-board-breadboards-yellow-10-piece-pack-139802?item=24[/url]
[url]http://www.dealextreme.com/p/prototype-universal-printed-circuit-board-breadboards-green-brown-10-piece-pack-136887?item=26[/url]

These are cheap and pretty low quality, you can get better ones made from fiberglass like these:

[url]http://www.dealextreme.com/p/double-sided-glass-fiber-prototyping-pcb-universal-board-3-x-7-5-piece-pack-131730?item=50[/url]
[url]http://www.dealextreme.com/p/double-sided-glass-fiber-prototyping-pcb-universal-board-5-pack-142733?item=42[/url]
But they're more expensive.

The ones I linked I found are among the best value packs I found, they also sell larger ones and in different size packs but one of the 10pc packs should last you about a half dozen projects.[/QUOTE]

Paper type prototyping boards have always been fine for me, just make sure you have a temperature controlled soldering iron or the pads may come falling off.

[Chryseus]

You'll get better value for money on some of those items shopping at a proper electronics distributor and faster delivery.
In particular you want more than 400 resistors, you don't need 50 crystals, fuse holders or 100 fuses.

Your missing transistors, op-amps, diodes, comparators, timers and logic gates.
DealExtreme is not that great a place for components unless you have specific needs.

[TTSDA]

[QUOTE=LoneWolf_Recon;36834154]Any good 30W soldering Iron will do for you(inb4 hate, RadioShack 30W irons are good if properly maintained). If you want to you can get you a full soldering station(I can't advise any good ones though)[/QUOTE]

Well, I suppose I want to get something that will last me for some time, so a full soldering station might be the best choice I think.

[QUOTE=chipset;36834551]Those copper clad PCD's are for etching, unless you know how to etch pcb's and have etching supplies you probably want to build up your projects after breadboarding on these:

[url]http://www.dealextreme.com/p/prototype-universal-printed-circuit-board-breadboards-brown-10-pack-132929?item=14[/url]
[url]http://www.dealextreme.com/p/prototype-universal-printed-circuit-board-breadboards-yellow-10-piece-pack-139802?item=24[/url]
[url]http://www.dealextreme.com/p/prototype-universal-printed-circuit-board-breadboards-green-brown-10-piece-pack-136887?item=26[/url]

These are cheap and pretty low quality, you can get better ones made from fiberglass like these:

[url]http://www.dealextreme.com/p/double-sided-glass-fiber-prototyping-pcb-universal-board-3-x-7-5-piece-pack-131730?item=50[/url]
[url]http://www.dealextreme.com/p/double-sided-glass-fiber-prototyping-pcb-universal-board-5-pack-142733?item=42[/url]
But they're more expensive.

The ones I linked I found are among the best value packs I found, they also sell larger ones and in different size packs but one of the 10pc packs should last you about a half dozen projects.[/QUOTE]

I have been reading about etching and I would like to learn but I think I'll add one of those too for good measure.

[QUOTE=Chryseus;36837210]You'll get better value for money on some of those items shopping at a proper electronics distributor and faster delivery.
In particular you want more than 400 resistors, you don't need 50 crystals, fuse holders or 100 fuses.

Your missing transistors, op-amps, diodes, comparators, timers and logic gates.
DealExtreme is not that great a place for components unless you have specific needs.[/QUOTE]

Do you recommend Bitsbox?

[Chryseus]

Bitsbox, RS, Farnell, Newark (if you're in the USA), Digikey and Rapid are all excellent suppliers.

[TTSDA]

[QUOTE=Chryseus;36837313]Bitsbox, RS, Farnell, Newark (if you're in the USA), Digikey and Rapid are all excellent suppliers.[/QUOTE]

Ok, then I'm getting from Bitsbox (I'm in Europe).
I'm a bit confused on which transistors to get, because there are so many different ones.

[Chryseus]

Having some NPN and PNP bipolar transistors such as the general purpose 2N3904 and 2N4403 is a good choice as well as some 2N7000 N-channel MOSFETs.
As for diodes I recommend 1N4007 and 1N4148, the first one is a rectifier diode used for general purpose and power application the other is used mainly with signals and low power.

For op-amps the LM324N is a popular choice and the LM311 is also a popular comparator.
If you're interested in building your own power supplies some zener diodes will come in handy as well as some LM317T adjustable voltage regulators and some power transistors such as the TIP31C, TIP41C, TIP42C and the IRF540.

As for other stuff get some 555 timers and anything else that looks interesting to you, I highly recommend their resistor and capacitor packs.

[Chipset]

Also add some potentiometers. Some of my first projects where power supplies and the like and if you wanna put it in a box and call it finished, those tiny trimpots from the dx order will be a bit of a hassle. You want the big ones that you can turn without the aid of a screwdriver. Half a dozen pots will do, 100k and 10k are fine values.

[Taipan]

Building a small speaker set.

Got some LM387 chips and components and tested them out:
[IMG]http://i34.photobucket.com/albums/d139/Taipan2/IMAG0288.jpg[/IMG]
Soldered them on a plate. (Dont have a soldering station, just a 7€ iron so the soldering isnt that good)
[IMG]http://i34.photobucket.com/albums/d139/Taipan2/IMAG0290.jpg[/IMG]
The back (its a re-used plate)
[IMG]http://i34.photobucket.com/albums/d139/Taipan2/IMAG0291.jpg[/IMG]
Building a stereo system in an old wine box, using 2 car speakers.
[IMG]http://i34.photobucket.com/albums/d139/Taipan2/IMAG0289-1.jpg[/IMG]
Will post some pix of the end product later.

[Torquil]

[QUOTE=Chryseus;36829132]I'd suggest learning the basics of electronics first, there is plenty of info in the op.[/QUOTE]

I tell a lie, I'm not entirely new, I meant I'm new to working with circuits myself, I've done a fair amount of the basic circuit principles at school (voltage, resistance, common components etc).

[chaz13]

Hopefully this is the right place to post this, as it's very basic and you guys are all rather knowledgeable (whereas I just got into electronics).

I'm looking to create a low pass filter (as an audio effect) and use a potentiometer to control the cutoff frequency.

Something like this:

[IMG]http://i50.tinypic.com/mhgkdf.png[/IMG]

My main two questions are- Would the circuit above work, and if so how do I know what are suitable values for the resistor and the capacitor that'd work fine with the signal from a guitar? (around 200mv)

The maximum cutoff frequency would be 20kHz as that's roughly where human hearing stops.

Thanks for the help!

[DrLuke]

[img]http://upload.wikimedia.org/wikipedia/de/math/c/5/1/c51664193b423b008b1af8493cd22122.png[/img]

Pluck in your capacity and resistance and you'll find the cutoff frequency.

With some simple math you'll find that R = 1 / ( f[SUB]c[/SUB] * 2PI * C).

[Chryseus]

[QUOTE=chaz13;36846656]Hopefully this is the right place to post this, as it's very basic and you guys are all rather knowledgeable (whereas I just got into electronics).

I'm looking to create a low pass filter (as an audio effect) and use a potentiometer to control the cutoff frequency.

Something like this:

[IMG]http://i50.tinypic.com/mhgkdf.png[/IMG]

My main two questions are- Would the circuit above work, and if so how do I know what are suitable values for the resistor and the capacitor that'd work fine with the signal from a guitar? (around 200mv)

The maximum cutoff frequency would be 20kHz as that's roughly where human hearing stops.

Thanks for the help![/QUOTE]

The cutoff frequency is given by 1 / (2 *Pi * R * C)
This is the frequency where the signal is attenuated by 3dB or half the input voltage.
Past the cutoff frequency the signal is attenuated at 6dB per octave or 20dB per decade so for example if you set your low pass filter to 10kHz you'll still get some of the higher frequency so it's not perfect.

Finally you really need a buffer on the output since any significant load will shift the cutoff frequency and the nice little equation becomes useless without modification, although since this is user adjusted and assuming the load is constant you can tweak it to compensate any loading effect on cutoff frequency.

You could stack multiple stages to give a sharper cutoff however this is much more complicated in terms of design, another potential option would be an active filter which allows much more control over the response and allows implementation of different filter topologies such as bessel or chebyshev.

[chaz13]

Thanks for the replies.

I already had an idea about the filter types and such (I've done software implementations).

I'm more worried about fucking it up due to my lack of electronics knowledge. So as that circuit should work, should I be looking to keep the resistance as low as possible so it doesn't have too much of an effect on the already small current, or is that not really an issue?

[Chryseus]

[QUOTE=chaz13;36847187]Thanks for the replies.

I already had an idea about the filter types and such (I've done software implementations).

I'm more worried about fucking it up due to my lack of electronics knowledge. So as that circuit should work, should I be looking to keep the resistance as low as possible so it doesn't have too much of an effect on the already small current, or is that not really an issue?[/QUOTE]

It's not really an issue unless the next stage impedance is less than 10x the value of R, 10k and 1uF should do the job nicely, that will give you a minimum cutoff frequency of about 16Hz, follow it up with a unity gain buffer and all will be well.

[SubbyV-2]

Hey guys, I'm just wondering what alternating current is? in term's of current direction

I have been rated funny (by chryseus and ddrl46) as I am currently arguing that alternating current is actually when the current periodically reverses direction rather than what they describe to be alternating current which is when the current goes from one voltage to another ( variate current).

[DrLuke]

[QUOTE=SubbyV-2;36852754]Hey guys, I'm just wondering what alternating current is? in term's of current direction

I have been rated funny (by chryseus and ddrl46) as I am currently arguing that alternating current is actually when the current periodically reverses direction rather than what they describe to be alternating current which is when the current goes from one voltage to another ( variate current).[/QUOTE]

Officially it must switch polarity periodically to be alternating, everything else is direct current.

[Ddrl46]

[QUOTE=SubbyV-2;36852754]Hey guys, I'm just wondering what alternating current is? in term's of current direction

I have been rated funny (by chryseus and ddrl46) as I am currently arguing that alternating current is actually when the current periodically reverses direction rather than what they describe to be alternating current which is when the current goes from one voltage to another ( variate current).[/QUOTE]

I didn't even talk to you, I just like rating you funny.

[SubbyV-2]

[QUOTE=ddrl46;36853094]I didn't even talk to you, I just like rating you funny.[/QUOTE]
Glad to hear you're mature.

[Ddrl46]

[QUOTE=SubbyV-2;36853123]Glad to hear you're mature.[/QUOTE]

No problem.

[Chryseus]

Subby was confused by me saying that that a pulsing uni-polar signal is alternating current, alternating does not strictly mean switching polarity it can also by definition mean between two levels, very few circuits are pure DC if you want anything interesting to happen, instead of taking my word for it he decided to ask Facepunch which in my opinion is not a very good idea as most of the people in this thread are fairly new to electronics, still at least I get to correct any misconceptions before other people fall into the same trap of thinking AC = alternating polarity or get it confused with voltage.

As far as circuit analysis is concerned anything that changes in current or voltage is treated as AC.

[SubbyV-2]

[QUOTE=Chryseus;36853444]Subby was confused by me saying that that a pulsing uni-polar signal is alternating current, alternating does not strictly mean switching polarity it can also by definition mean between two levels, very few circuits are pure DC if you want anything interesting to happen, instead of taking my word for it he decided to ask Facepunch which in my opinion is not a very good idea as most of the people in this thread are fairly new to electronics, still at least I get to correct any misconceptions before other people fall into the same trap of thinking AC = alternating polarity or get it confused with voltage.

As far as circuit analysis is concerned anything that changes in current or voltage is treated as AC.[/QUOTE]
You're arguing with wikipedia.
There is more definitions to describe electrical current then just AC and DC.

[DrLuke]

[url]http://upload.wikimedia.org/wikipedia/commons/3/38/Types_of_current.svg[/url]

[editline]20th July 2012[/editline]

Just to clear it up: "variable" switches polarity, but it doesn't do it periodically, so it still is DC.

[SubbyV-2]

[QUOTE=DrLuke;36853802][url]http://upload.wikimedia.org/wikipedia/commons/3/38/Types_of_current.svg[/url]

[editline]20th July 2012[/editline]

Just to clear it up: "variable" switches polarity, but it doesn't do it periodically, so it still is DC.[/QUOTE]

Chryseus will never admit he is wrong, he has no source except saying electrical engineers multiple times.
Also juicy lol factor:
[QUOTE=chryseus]
Porch Monkey: this isnt going anywhere since you wont get over the fact you have no source
Chryseus - 2 Days: I do
Chryseus - 2 Days: myself
Chryseus - 2 Days: since I'm always right
[/QUOTE]

[Chryseus]

[QUOTE=DrLuke;36853802][url]http://upload.wikimedia.org/wikipedia/commons/3/38/Types_of_current.svg[/url]

[editline]20th July 2012[/editline]

Just to clear it up: "variable" switches polarity, but it doesn't do it periodically, so it still is DC.[/QUOTE]

Agreed, the confusion comes with the pulsing waveform, some might call it DC however I stick to calling it AC since that's what you would analyse it as and the current does alternate between two levels.

[DrLuke]

[quote=wikipedia]In alternating current (AC, also ac), the movement of electric charge periodically reverses direction. In direct current (DC, also dc), the flow of electric charge is only in one direction.[/quote]

[url]http://en.wikipedia.org/wiki/Alternating_current[/url]

[chaz13]

[QUOTE=Chryseus;36852513]It's not really an issue unless the next stage impedance is less than 10x the value of R, 10k and 1uF should do the job nicely, that will give you a minimum cutoff frequency of about 16Hz, follow it up with a unity gain buffer and all will be well.[/QUOTE]

Final question - had a quick wikipedia but I couldn't quite work it out. What's the unit gain buffer do and what'd happen without it?

[DrLuke]

[QUOTE=Chryseus;36853897]Agreed, the confusion comes with the pulsing waveform, some might call it DC however I stick to calling it AC since that's what you would analyse it as and the current does alternate between two levels.[/QUOTE]

Well, it's still DC.

[Chryseus]

[QUOTE=chaz13;36853926]Final question - had a quick wikipedia but I couldn't quite work it out. What's the unit gain buffer do and what'd happen without it?[/QUOTE]

Unity gain buffer, it prevents the load effecting the cutoff frequency, essentially it looks like a very high value resistor to the filter so it does not load it, but to the load it looks like a very small resistor so it can easily drive it.

[url=http://www.falstad.com/circuit/#%24+1+5.0E-6+35.60246606707791+50+5.0+50%0Aa+304+256+416+256+1+5.0+0.0+1000000.0%0AR+160+240+112+240+0+1+40.0+0.2+0.0+0.0+0.5%0Aw+304+272+272+272+0%0Aw+272+272+272+336+0%0Aw+272+336+416+336+0%0Aw+416+336+416+256+0%0Ar+544+256+544+304+0+1000.0%0Ag+544+304+544+320+0%0Ac+416+256+480+256+0+1.0E-5+2.433909480872063%0Aw+480+256+544+256+0%0Ar+240+240+240+176+0+10000.0%0Ar+240+240+240+304+0+10000.0%0AR+240+176+240+128+0+0+40.0+5.0+0.0+0.0+0.5%0Ag+240+304+240+320+0%0Aw+240+240+304+240+0%0Ac+160+240+240+240+0+1.0E-5+-2.5158137464252714%0Ax+67+169+194+174+0+19+Input+from+filter%0Ax+534+228+627+232+0+18+Output+load%0Ax+290+194+489+198+0+18+General+purpose+op-amp%0Ao+6+64+0+34+0.3125+9.765625E-5+0+-1%0A]Like this[/url]

[LoneWolf_Recon]

[QUOTE=Chryseus;36854136]Unity gain buffer, it prevents the load effecting the cutoff frequency, essentially it looks like a very high value resistor to the filter so it does not load it, but to the load it looks like a very small resistor so it can easily drive it.

[url=http://www.falstad.com/circuit/#%24+1+5.0E-6+35.60246606707791+50+5.0+50%0Aa+304+256+416+256+1+5.0+0.0+1000000.0%0AR+160+240+112+240+0+1+40.0+0.2+0.0+0.0+0.5%0Aw+304+272+272+272+0%0Aw+272+272+272+336+0%0Aw+272+336+416+336+0%0Aw+416+336+416+256+0%0Ar+544+256+544+304+0+1000.0%0Ag+544+304+544+320+0%0Ac+416+256+480+256+0+1.0E-5+2.433909480872063%0Aw+480+256+544+256+0%0Ar+240+240+240+176+0+10000.0%0Ar+240+240+240+304+0+10000.0%0AR+240+176+240+128+0+0+40.0+5.0+0.0+0.0+0.5%0Ag+240+304+240+320+0%0Aw+240+240+304+240+0%0Ac+160+240+240+240+0+1.0E-5+-2.5158137464252714%0Ax+67+169+194+174+0+19+Input+from+filter%0Ax+534+228+627+232+0+18+Output+load%0Ax+290+194+489+198+0+18+General+purpose+op-amp%0Ao+6+64+0+34+0.3125+9.765625E-5+0+-1%0A]Like this[/url][/QUOTE]

If you feel up to it you can further increase the cutoff by making a Sallen-Key Butterworth filter its essentially two low passes and a unity gain buffer smacked together. So if you happen to have a dual op-amp(I recommend the TL272CP). Then you can do this as well:

[URL="http://en.wikipedia.org/wiki/Butterworth_filter#Sallen.E2.80.93Key_topology"]Sallen-Key Butterworth - Wiki[/URL]

But, one thing at a time so go with Chryseus's recommendation first

[MIPS]

Something fell over last night and woke up everyone in the house.

[IMG]http://i11.photobucket.com/albums/a166/ballsandy/100_2992.jpg[/IMG]

...Fuck. I just got the flickering fixed on it too. :(