Searching for electronics today international article. February 1987

Thread Starter

Fenris

Joined Oct 21, 2007
288
Hi all

I have recently stumbled across a schematic for a solid state LED matrix oscilloscope. I remember the original article my self :D . But does anyone have a scan they could pass on to me please. Mainly to do with the details of using this particular unit when built. I remember wanting to build it back then but the 100 LED's were going to cost an arm and a leg back then! So I fancy doing it now I can afford them :D

regards

Fenris
 

Attachments

Audioguru

Joined Dec 20, 2007
11,248
If it has a 10V supply then the typical output current from the CD4017 is 17mA.
Multiplexing will reduce the average current in each LED to only 1.7mA which will look pretty dim. Maybe you can use the 'scope in the dark.
 

eblc1388

Joined Nov 28, 2008
1,542
Hi Audioguru,

If it has a 10V supply then the typical output current from the CD4017 is 17mA.
That value of typical current 17mA is quite high. Does any datasheet shows this figure?

@Fenris,

Some high brightness LEDs can provide acceptable brightness at current of a few milliamps. Check them out.
 

Audioguru

Joined Dec 20, 2007
11,248
The datasheets of Cmos logic ICs from Texas Instruments show minimum and typical output current when the supply is 5V, 10V and 15V.
With a 10V supply the output current into a 3.5V white or blue LED is 17mA without a current-limiting resistor. The output transistor dissipates 110mW which is slightly above its max allowed dissipation of 100mW. It would be fine with a 9V supply.
 

Attachments

Top