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Advance Modification: Dahua SD49225T-HN Adding External Microphone Power
Advance Modification Disclaimer - I successfully performed this modification, but this should only be undertaken with the understanding that you may damage your camera permanently. Only those who are able to cleanly solder and have an understanding of electronic component work should even consider doing this mod. You are solely responsible for any damages caused by doing this modification.
This modification provides 12 volt microphone power out of what is normally just the DC 12 volt input jack. It does so by tapping into the POE 12 volt supply with a 480 ohm resistor and feeding that to the DC input +12 lead. A 100 mfd capacitor filters noise in the supplied power. Only a very small current draw is allowed through the resistor (about 25 ma even if short circuited, but it readily powers a Micro seven external microphone. I detected no hum from the audio input when the microphone is thus powered.
The modification also allows the DC input to be used as a DC input. However, this mod would only be useful if one wanted to let the camera's POE+ supply to power an external mic.
Materials required:
1 - 480 ohm 1/8 watt resistor (alt 1/4 watt is also OK)
1 - 100 mfd 16 volt electrolytic capacitor. (Spec not critical. 100-200 mfd, 16 to 32 volts OK)
Remove screws holding the top dome cover in place. Remove top cover and disconnect cable connectors. The two connectors each have a squeeze release latch.
Look out for the white heat transfer pad. You MUST protect that from getting damaged or contaminated. Also, it MUST be put back in position during reassembly to heatsink the POE board.
Advance Modification Disclaimer - I successfully performed this modification, but this should only be undertaken with the understanding that you may damage your camera permanently. Only those who are able to cleanly solder and have an understanding of electronic component work should even consider doing this mod. You are solely responsible for any damages caused by doing this modification.
This modification provides 12 volt microphone power out of what is normally just the DC 12 volt input jack. It does so by tapping into the POE 12 volt supply with a 480 ohm resistor and feeding that to the DC input +12 lead. A 100 mfd capacitor filters noise in the supplied power. Only a very small current draw is allowed through the resistor (about 25 ma even if short circuited, but it readily powers a Micro seven external microphone. I detected no hum from the audio input when the microphone is thus powered.
The modification also allows the DC input to be used as a DC input. However, this mod would only be useful if one wanted to let the camera's POE+ supply to power an external mic.
Materials required:
1 - 480 ohm 1/8 watt resistor (alt 1/4 watt is also OK)
1 - 100 mfd 16 volt electrolytic capacitor. (Spec not critical. 100-200 mfd, 16 to 32 volts OK)
Remove screws holding the top dome cover in place. Remove top cover and disconnect cable connectors. The two connectors each have a squeeze release latch.
Look out for the white heat transfer pad. You MUST protect that from getting damaged or contaminated. Also, it MUST be put back in position during reassembly to heatsink the POE board.
