idiots guide to circuit boards
Discussion
I need to make a simple circuit but have not done electronics since secondary school, and never made any circuits then.
I have a few simple ( to those who know) questions:
Which leg of an LED is to +ve, and which to -ve? Long or short?
On a diode how do i know way round to put it?
How do i know which way round a resistor goes?
This is the cirucit i am trying to build, but failed badly and it wont work. Please tell me hat i di wrong!
http://forums.xpowerforums.com/attachment.php?atta...
I have a few simple ( to those who know) questions:
Which leg of an LED is to +ve, and which to -ve? Long or short?
On a diode how do i know way round to put it?
How do i know which way round a resistor goes?
This is the cirucit i am trying to build, but failed badly and it wont work. Please tell me hat i di wrong!
http://forums.xpowerforums.com/attachment.php?atta...
gti tim said:
Which leg of an LED is to +ve, and which to -ve? Long or short?
long is +gti tim said:
On a diode how do i know way round to put it?
the stripe denotes the end that the arrow points to in the symbolgti tim said:
How do i know which way round a resistor goes?
does not matter which way round they gogti tim said:
This is the cirucit i am trying to build, but failed badly and it wont work. Please tell me hat i di wrong!
http://forums.xpowerforums.com/attachment.php?atta...
cannot see that needs a logonhttp://forums.xpowerforums.com/attachment.php?atta...
Edited by dogbucket on Sunday 18th January 17:52
Could i have overheated components?
My circuit is basically this:
+ve input - LED - diode -}
+ve input - LED - diode -}
+ve input - LED - diode -} resistor - earth (same one for all 4 inputs)
+ve input - LED - diode -}
LEDSs correct way round, diodes correct way round, all good solders to each component, but it wont work when tested
The purpose of the circuit is to indicate when the variable valve system on my inlets is working, as its a known problem area on the car (MG ZS 180)
My circuit is basically this:
+ve input - LED - diode -}
+ve input - LED - diode -}
+ve input - LED - diode -} resistor - earth (same one for all 4 inputs)
+ve input - LED - diode -}
LEDSs correct way round, diodes correct way round, all good solders to each component, but it wont work when tested
The purpose of the circuit is to indicate when the variable valve system on my inlets is working, as its a known problem area on the car (MG ZS 180)
Sounding like a real idiot here - but what type of circuit board would i need? trying to order from maplins site, and there are loads of different types and i dont know what is what. All i want to do is build this simple circuit, and i cant even work out what type of board i need to do it with 
Dan - voltage is 12v ( car battery), diodes are there to protect ECU should LEDs fail, resistor is 2k, 0.6w (whatever that means)
would this board be ok?
http://www.maplin.co.uk/Module.aspx?ModuleNo=1917
would this board be ok?
http://www.maplin.co.uk/Module.aspx?ModuleNo=1917
Edited by gti tim on Sunday 18th January 19:44
I'd use a little bit of veroboard, matey (the stuff above would be OK, make sure you get it with copper strips on one side). You'll need a copper track strip cutter for it as well.
When soldering, heat up the pin and cct board track together with a clean iron bit (tinned, i.e. with clean fresh solder coating on the bit. Keep cleaning it and applying a bit of solder now and then to keep it shiny) then apply the solder so that it melts and flows over pin & track. Once it's flowing you'll only need a fraction of a second of this before removing solder then iron. Should give a clean, bright joint. If it's a dull or lumpy join it's gone dry (no flux) and may not conduct. Use a solder sucker or desoldering braid (better IMO), remove it all and start again. Don't 'reheat' a solder joint as the flux will eventually disappear.
Try not to apply soldering heat to the legs of semiconductor components for too long as you'll cook then internally. You'll have to be going some to destroy an LED in this way though.
Have fun.
When soldering, heat up the pin and cct board track together with a clean iron bit (tinned, i.e. with clean fresh solder coating on the bit. Keep cleaning it and applying a bit of solder now and then to keep it shiny) then apply the solder so that it melts and flows over pin & track. Once it's flowing you'll only need a fraction of a second of this before removing solder then iron. Should give a clean, bright joint. If it's a dull or lumpy join it's gone dry (no flux) and may not conduct. Use a solder sucker or desoldering braid (better IMO), remove it all and start again. Don't 'reheat' a solder joint as the flux will eventually disappear.
Try not to apply soldering heat to the legs of semiconductor components for too long as you'll cook then internally. You'll have to be going some to destroy an LED in this way though.
Have fun.
Edited by speedtwelve on Sunday 18th January 19:48
speedtwelve said:
I'd use a little bit of veroboard, matey (the stuff above would be OK, make sure you get it with copper strips on one side). You'll need a copper track strip cutter for it as well.
You can also use a sharp 4-5mm drill to cut the tracks also.You could also do what we used to call "christmas treeing" - where you just solder each component to each other and dont bother with the strip board (bodgetastic)
gti tim said:
Dan - voltage is 12v ( car battery), diodes are there to protect ECU should LEDs fail, resistor is 2k, 0.6w (whatever that means)
What spec LEDs have you got also? Normals are around 1.7v 20mA, but then you get a huge variety of super bright etc!Edited by gti tim on Sunday 18th January 19:42
Assuming they are 1.7v, and you're motor is 12.5v when running, you need to drop 10.8v, so 10.8 x 0.02 (20mA) gives you 540ohms resister to get the right voltage. LEDs are very fussy about what they are fed with. This isn't taking into account the diodes, but LEDs are diodes themselves so you don't really need them!
p.s. trying to remember myself! It's been 15years since I did any electronics in anger!
Edited by _Dan_ on Sunday 18th January 19:57
gti tim said:
Could i have overheated components?
My circuit is basically this:
+ve input - LED - diode -}
+ve input - LED - diode -}
+ve input - LED - diode -} resistor - earth (same one for all 4 inputs)
+ve input - LED - diode -}
LEDSs correct way round, diodes correct way round, all good solders to each component, but it wont work when tested
The purpose of the circuit is to indicate when the variable valve system on my inlets is working, as its a known problem area on the car (MG ZS 180)
Buy a different car. Cheaper and quicker in the long run. Save yourself a load of hassle.My circuit is basically this:
+ve input - LED - diode -}
+ve input - LED - diode -}
+ve input - LED - diode -} resistor - earth (same one for all 4 inputs)
+ve input - LED - diode -}
LEDSs correct way round, diodes correct way round, all good solders to each component, but it wont work when tested
The purpose of the circuit is to indicate when the variable valve system on my inlets is working, as its a known problem area on the car (MG ZS 180)
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