Hello all hope you will be able to help me. I need to build a Double 7 segment led to read the number 95 thats all a static display. But not sure what i will need and how to make it work.
I know i will need a double led i will use this type: http://www.maplin.co.uk/Module.aspx?ModuleNo=2166
the Common Cathode type

i dont know what conections on that unit will display 95 (but think you will)
the unit will be powerd by a 9 volt battery or maybe 2aa batterys (what is best ?)
it will have an on and off switch. This is simple i can do
Now to resitors i know i need them so not to blow my led up .If i can use one single resistor that would be best and maybe have many wires coming from that to the lcd display. But I need to know what size and type resistor to buy. thats if it can be done.

i would like to wire everything directly to the led display i dont want to make a circit board.

so if you can help that will be great. if you need any extra info i will do my best to help you.

thanksgary

 

Follow the link and get the data sheet - http://www.westfloridacomponents.co...D+Display+Common+Mode+Dual+Red+HD5P-5321.html Your display should follow the pinout. Each used segment line will need a current limiting resistor. 2 AA's will last longer than the 9 volt battery. Use 150 ohm 1/4 watt resistors. You can experiment with the batteries and one resistor to see which segments light up.

 

do i conect the + of the battery to the led bord then the resistors form a point on the bord. and the battery to -

 

The segments have LED's for the light. All those LED's have their cathodes tied to the common cathode pin. Make you resistor hookups as in the examples in the Ebook section on LED's - http://www.allaboutcircuits.com/vol_3/chpt_3/12.html

 

still a bit confused. i can get the led segments to light up but not sure where to go next.
here is a little diagram.
0= PIN 1
9= PIN 9
R= PIN 10
X= PIN 18
D- des point on front of display


0 I I I I I I I 9



D D

R I I I I I I I X


pin 5 i think is earth or ground.
how do i do the resistors do i, from + wire of the battery add a resistor to pin 0, then a resistor from pin 0 to say pin 11 then another resistor from pin 11 back to pin 5 earth making the circuit complete.

hope this makes sence

 

The common cathode goes to the battery negative terminal. The positive voltage is applied through individual resistors to the LED segments, also individually.

To make a 9 means lighting segments a, b, c, & f. A 5 uses a, f, g, c, & d. Look at the data sheet.

 

thanks for all the help. i now have a double counter that that is reading 95.
but have done it like this the from the + battery to a pin then i have conected all the pins i needed with a strand of wire. then found an - that makes them all lite up. did use a resistor but the led lights up real dim. removed the resistor and conected to the led now nice and bight. the led is now using no resistors, but dose feel a bit warm, has been displaying 95 now for over an hour with no resistors without any problems apart from dose feel a tad warm.
do you recomend using a smaller resistor ?