[sdiy] Improving LED response when driven from half-wave rectifier

[Stewart Pye]

Hi Justin,

Yes. Use the non inverting VCCS. LED in feedback loop, current setting 
resistor from - input to GND, input to + input.  (Fig 4.2 in Op Amp 
Cookbook 3rd Ed).
If you put the LED's back to back you can do away with the half wave 
rectifiers so all you need is one op amp. Just make sure the op amp you 
use can supply the required current. You could use a bicolour LED so 
It's red when +ve and green when -ve.

Regards,
Stewart.




On 9/5/2012 8:32 PM, Neil Johnson wrote:
> Justin Owen <juzowen at gmail.com> wrote:
>> Ah - putting it in the feedback loop? The same way you would with a Vactrol? Yes - I'll take a look at that.
> Yep.  Bonus points if you do it so that the LED driver circuit does
> not load the signal it is monitoring.
>
> Neil