How can I fade the 7-seg displays using the blanking input on 14513 & photo-resistor?

[velson]

How can I fade the 7-seg displays using the blanking input on 14513 & photo-resistor?

Hi!

How can I fade the 7-seg displays using the blanking input on the 14513 and a photo-resistor?

So far I did a trick with an oscillator to lower the duty-cycle using one of the 74C14 NOT gates but I need the opposite effect. Now I get a brighter display with brighter light and I want to dim the displays when it's dark. Any ideas?

Also, is there a way to speed up the update rate on those displays (faster than the default 1/sec)?

Thanks

 

[laktronics]

Re: 7-seg display fader

Hi,
If you have already implemented a PWM scheme to control the display brightness depending on the ambient light, it should work either way, that is the brightness should fall automatically when the ambient light reduces, where is the problem?
As regards display update, it can be updated as fast as half a micro second from the latch loading point by application of LE- signal. Where is the one sec limit coming from?

Regards,
Laktronics

 

[velson]

Re: 7-seg display fader

Sorry I got u confused, my bad! That's just stupid what I wrote!

I meant I get a brighter display when it's dark, when it should be the opposite. Man, I hope I got it right this time, let me read it again.

Yeah, that's it. So how can I reverse the effect? There are no photo-resistors with greater resistance by increase of light, correct me if I'm wrong. But that's just what I need, or an alternative that I don't know of.

 

[laktronics]

Re: 7-seg display fader

Hi,
I think that should be quite easy, use a transistor or amplifier to invert the signal and then apply it to the PWM to drive the blanking signal? Or, even simpler, use it as a potential divider with another resistor and use it in the upper or lower arm of the divider.
Regards,
Laktronics