TWO LEDS - METER for overload signal - help needed!

Here is what I have so far. Does it make any sense?

CLICK ON THE PICTURE FOR BETTER VIEW



I don't know how to wire the dual LED to the existing schematics. The idea is to have first LED light when + 3dB and the second when +6dB of output gain in my G-SSLs. I will put this meter only to the left channel of the output signal.

wouldn't it be more simple to use lm3914?

Well maybe but I already have all the components and I don't want to change the plan again for all 12 units at this stage. This simple schematic is back from the school days.... I just don't know how to wire the dual LED. Any experts around here?

untill some expert pop up i'll say suplay voltage to the + and connect each - to it's own transistor, you might need a bigger droping resistor depending on your led input voltage.

btw did you checked that your led really works this way? , i have a bi color led that have a common "-" not positive.

adding some b c e sign's might help not that it's to hard to guess.

[quote author="yan_b"]adding some b c e sign's might help not that it's to hard to guess.[/quote]

Updated the picture above, thanks.

[quote author="yan_b"]adid you checked that your led really works this way? , i have a bi color led that have a common "-" not positive. [/quote]

You mean that the - is the middle leg, and the other two are + ?

This is the LED http://www.us.kingbright.com/product.asp?catalog_name=LED&product_id=W59EGW

BTW, could you make a simple drawing of all your suggestions?

look at the spec's http://www.us.kingbright.com/images/catalog/SPEC/W59EGW.pdf

Yes, I checked the pdf, the middle leg is anode "-".

yan_b is this what you suggested?

warnning major simplification !

think about it like that, the transistor act as a switch or valve between the collector and emitter, the base current just control the valve.

you have to supply current to the led and pass it through the transistor, in this case it's a problem cause this configuration supose to pass only from positive to negative.
maybe you can modify the cuircit to pnp transistors some how, but i don't know enough to help you with that.

I got new idea from a friend since the middle leg is the only anode, which means "+"



Does it make sense now? I would like to hear a second opinion before soldering all components :thumb:

do you have a breadboard? Maybe just try the circuit out a few times on the breadboard then decide which is best

It's going to stay on the perfoboard at the end anyway so I might just go for it and see if it works...

Maybe you can modify this to accomplish your goal (the LED circuit is in the upper right-hand part of the schematic):

http://www.rane.com/pdf/ms1bsch.pdf

[quote author="Flatpicker"]Maybe you can modify this to accomplish your goal (the LED circuit is in the upper right-hand part of the schematic):

http://www.rane.com/pdf/ms1bsch.pdf[/quote]

Thanks. I might follow the design on the rane schematic but than I have to change the whole plan and buy new components... and I don't want to do this.

Anyway, maybe the picture of the original plan can help some of you experts figure it out how to wire the BI-colored LED.

[quote author="Purusha"]I got new idea from a friend since the middle leg is the only anode, which means "+"



Does it make sense now? I would like to hear a second opinion before soldering all components :thumb:[/quote]

Transistor is working like a "remote" switch and in this case the 1uF capacitors are conected wrong. They should be conected paralell to the ground to keep the peek on long enough for you to see it.
I think its best that you try to hook up LED to some voltage to test it. If its common cathode, we can rearange the shematic.

Regards

Thanks, can you be more specific about where to connect the "+" leg of electrolytics, if the "-" leg goes to the ground?

I'll test the LEDs and report back.

OK, the middle leg of the LED is 100% sure "-" cathode.

So what to re-arrange now in my schematic?

[quote author="Purusha"]Thanks, can you be more specific about where to connect the "+" leg of electrolytics, if the "-" leg goes to the ground?

I'll test the LEDs and report back.[/quote]

+ leg on the capacitor should be conected after the 1k resistor, so that base on the transistor stays opened a litlle bit longer.

[quote author="Purusha"]OK, the middle leg of the LED is 100% sure "-" cathode.

So what to re-arrange now in my schematic?

[/quote]

about the dual led thing, we can work it out with some pnp transistors. BC557 can be used also, thing is a bit more complicated, but i think you will manage it. I will draw you a shematic later on tonight. or if it easier for you, you can try to find dual LED with common anode.

Schematic would be great. I will also ask tommorrow if I can exchange my 12 LEDs with the one you mentioned. Otherwise if you can come up with some solution for my LEDs and pnp transistors it will be fine too.

Thank you mister :thumb: