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Need help with very basic CMOS open drain circuit

SUREN GUNARATNE

Jan 20, 2015
2
Joined
Jan 20, 2015
Messages
2
Hi,

Diagram 1 in the attachment shows a typical usage of the circuit.
Diagram 2 is what I intend to do which I'm not sure if it is possible.

1) Need to know if the circuit in the diagram 2 of the attachment is ok or else how can that be modified to use the open drain outputs of the controller perhaps as an OR gate. Please bare in mind that my electronics knowledge does not go beyond Ohm's Law. Therefore do not give much weight to the usage of "OR gate".

The LED controller is designed to control strips of RGB lights and hence it has three separate outs to control (on/off, dim, strobe, fade) each color individually. Outputs are Open-drain CMOS with a common 12V positive. The controller is sealed and does not know what's inside.

I'm using a strip of white LED lights attached to a LED controller to lite-up my Record Player. In addition to have the ability to control the lights with the remote by connecting to output "R", I like to tie the light strip to another out (say, B) via a switch that is connected to the Tone Arm of the player. When the tone arm is raised the switch is on, and it is off when the record is playing or when the tone arm is at rest. If I need the light on while the record is playing, then I can still turn the light on with the remote by turning output "R" on.

2) If I want to dim the light further, can I use a resistor in series between the output R and the LED strip.

Thanks for every one in advance.
 

Attachments

  • LED Light Strip.pdf
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Harald Kapp

Moderator
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Nov 17, 2011
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Welcome to electronicspoint.

Although your setup look a bit unusual, it should work.
Instead of using a series resisitor for dimming, you can just set the "B" output to a lesser brightness (assuming you can control R,G and B individually which depends on your controller/remote).
 

SUREN GUNARATNE

Jan 20, 2015
2
Joined
Jan 20, 2015
Messages
2
Thanks Harald. The lowest preset brightness level is still a bit too bright. That's the reason I'm thinking of using a resistor.
 
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