• Electronics and Embedded Programming V3
    1,545 replies, posted
  • [QUOTE=VistaPOWA;35937274][img]http://media.fukung.net/images/14462/4225b64d90300cbe4277eae166cc355d.gif[/img] why[/QUOTE] That person clearly doesn't understand the vacuum aspect of vacuum tubes.
  • IT'S A VACUUM TUBE, IT WILL SURELY WORK IN AIR TOO HURR DURR. [editline]13th May 2012[/editline] Apparently, one piece of that type of tube costs about $40. [url]http://www.ebay.com/itm/Westinghouse-7591-A-Tubes-Tested-Strong-Matched-Pair-USA-7591A-Tubes-Valves-1966-/370611031081?pt=Vintage_Electronics_R2&hash=item564a238c29#ht_2203wt_1177[/url] He just ruined $320 worth of electronics.
  • It's probably just someone who had an already broken tube and decided to pull a funny.
  • [QUOTE=ddrl46;35936714]If you don't want to blow the leds up you might want to get some resistors (470 and 1k are nice values).[/QUOTE] Right, I'll buy some of those then too. [editline]13th May 2012[/editline] I still need a good electronics shop too, I'm in the Netherlands and I don't want to spend 10 euro shipping costs for a 4 euro order.
  • Try finding a local shop that sells electronic components and buy from there instead. [editline]13th May 2012[/editline] I also recommend Tayda Electronics, cheap prices and free shipping: [url]http://www.taydaelectronics.com/[/url]
  • [QUOTE=VistaPOWA;35937900]Try finding a local shop that sells electronic components and buy from there instead. [editline]13th May 2012[/editline] I also recommend Tayda Electronics, cheap prices and free shipping: [url]http://www.taydaelectronics.com/[/url][/QUOTE] Ah, thanks, that's very cheap indeed.
  • [QUOTE=Staneh;35931586]Right, so I'm planning to buy an Arduino Uno, with cables, leds and a breadboard to start with, am I missing something to just start off with?[/QUOTE] Resistors, capacitors, diodes, transistors, op-amps, 74xxxx / 4xxx series logic, sensors, etc Assuming you plan on doing anything other than lighting up a few LEDs Get a good selection of components, there is nothing worse that finding you don't have the correct component on hand.
  • [QUOTE=VistaPOWA;35937274][img]http://media.fukung.net/images/14462/4225b64d90300cbe4277eae166cc355d.gif[/img] why[/QUOTE] Oh my god... That can't be real. No body is that stupid... :|
  • Is there anyone I can add to maybe ask some basic questions about electronics? I've got some, and more will probably follow.
  • Why don't you just go ahead and post them? If they are some basic questions then i can assure you that you will get the answers.
  • Right, here is one: What's the difference between a 1/4W resistor, a 1/2W resistor and a 1W resistor?
  • Ah, okay, I'm going to watch some videos on basic electronics, my arduino should be arriving around 31may.
  • The difference basically is it's size. The bigger it is, the more power it can dissipate without failing in a catastrophic manner (smoke, fire, explosions). I suggest you get 1/4 W resistors, they're all you ever going to need to the beginning.
  • [QUOTE=Staneh;35941802]Right, here is one: What's the difference between a 1/4W resistor, a 1/2W resistor and a 1W resistor?[/QUOTE] The difference is the maximum power the resistor can dissipate before it fails.
  • [QUOTE=Ragy;35945236]The difference is the maximum power the resistor is dissipate before it fails.[/QUOTE] And what about Metal Film Resistors and Carbon Film Resistors?
  • [QUOTE=Staneh;35945315]And what about Metal Film Resistors and Carbon Film Resistors?[/QUOTE] Metal and carbon resistors are just two of multiple types of materials resistors are constructed of, each containing different resistance, power dissipation, and shape properties. As a beginner, just stick to carbon composite resistors, as they are very affordable, durable, and common.
  • [QUOTE=Ragy;35945380]Metal and carbon resistors are just two of multiple types of materials resistors are constructed of, each containing different resistance, power dissipation, and shape properties. As a beginner, just stick to carbon composite resistors, as they are very affordable, durable, and common.[/QUOTE] To add to Ragy, Carbon Composites are also 'purely' resistive compared to metal film resistors. That is, Metal films have small capacitive and inductive properties that can foul with high frequency circuits. But as Ragy said, you need not worry about the material now.
  • Resistors have eight basic properties, which depending on what you're doing are worth knowing: Resistance measured in Ohms Maximum voltage rating Tolerance (how close the resistance should be to the marked value, given in %) Temperature coefficient (how much resistance changes with temperature, given in parts per million) Voltage coefficient (how much resistance varies with applied voltage, also measured in ppm) Long term stability (the degree to which resistance drifts over time, measured in ppm) Noise (the amount of thermal noise and 1/f noise generated by the resistor, given in V/sqrt(Hz). Lead inductance / capacitance. Some of the common types of resistors are: [b]Carbon film[/b] These are your generic cheap resistors, usually available up to 1W and with a tolerance of 5% or more, they have moderate noise and fairly poor temperature coefficient so should be avoided where precision and noise are of concern, but for everything else I'd recommend them. [b]Metal film[/b] Similar to the carbon film but with significantly better characteristics, tolerances of 1% are standard so these should be used in circuits where good accuracy and low noise are desired. These are easily identified by their blue coating. [b]Wirewound[/b] These can either be designed for power or accuracy, some can handle several hundred watts or have tolerances better than 0.05%, they are also extremely stable long term and handle overloads well, they however tend to have poor high frequency response due to high inductance. Resistors also come in series such as the E6, E12 or E24 series, for a beginner I'd recommend you at least have a decent amount of E12 series resistors, 1/4W carbon film should do the job fine for pretty much anything you'll be doing, getting some 1% metal film would be quite useful however, at least in the commonly used 1k, 10k and 100k values. Now I'm going to sleep it's 2am :v:
  • I seem to have run into a little problem. I connected a transistor as a switch, which is switching a 12V psu that controls a 12V DC relay. The relay refuses to switch on when the transistor is supposed to close the circuit. I am measuring the 12V going trough the transistor and arriving at the relay yet it remains inactive. If i connect the psu without the transistor then the relay works just fine. Does anybody have an idea What could be wrong?
  • [IMG]http://dl.dropbox.com/u/64443729/ele/Relais.PNG[/IMG] This should be it. [editline]w[/editline] Q1 is not constantly powered, a separate circuit enables it by sending 3.9V
  • [QUOTE=0lenny0;35968591][IMG]http://dl.dropbox.com/u/64443729/ele/Relais.PNG[/IMG] This should be it. [editline]w[/editline] Q1 is not constantly powered, a separate circuit enables it by sending 3.9V[/QUOTE] Nevermind, drawing something. Try this: [img]http://i.imgur.com/Nneqc.png[/img]
  • You should also be using a general purpose transistor not a power high voltage transistor which tend to have poor current gain. The parallel diode across the relay that Ddrl added is also critical, without it you risk damage to the transistor.
  • I know that i need to use a diode across the relay to prevent damage but it should work even without it. The diode is only needed for when the relay is going to be switched off. I can't even seem to get it to switch on a.t.m.
  • [QUOTE=0lenny0;35969539]I know that i need to use a diode across the relay to prevent damage but it should work even without it. The diode is only needed for when the relay is going to be switched off. I can't even seem to get it to switch on a.t.m.[/QUOTE] If you build it like ddrl's circuit above it should work, unless you're doing something seriously wrong. Oh wait I just noticed, why is the collector supply the wrong way around... No wonder you're having issues. I suggest you do some reading before you blow something up > [url]http://www.allaboutcircuits.com/[/url]
  • [QUOTE=Chryseus;35968919]You should also be using a general purpose transistor not a power high voltage transistor which tend to have poor current gain. The parallel diode across the relay that Ddrl added is also critical, without it you risk damage to the transistor.[/QUOTE] It's not just a risk, it WILL happen
  • Not necessarily, assuming an inductance of 200mH, a coil current of 200mA and a discharge time of 1ms it will product a maximum voltage of 40V.
  • [QUOTE=Chryseus;35970256]Not necessarily, assuming an inductance of 200mH, a coil current of 200mA and a discharge time of 1ms it will product a maximum voltage of 40V.[/QUOTE] Which, depending on the transistor he's using, may/may not damage the transistor. Better safe than sorry. In the case of the transistor he used he would be fine, but it's still good habit to add such safeties.