H100: Auto power-on on USB or AC adapter connection

[XavierGr]

I have both an H300 and H100 and I have noticed that the H300 has one cool feature. It will power-on while you insert the USB cable or the AC adapter.

Is it possible to mod the H100 to do the same? I think that by providing voltage on the "PLAY" pad (on the back of the motherboard) then the player will turn on. The alarm part of the RTC mod does exactly this.

The problem is that in order for it to work properly the voltage signal must not be constant. Upon connection it must give a signal and then stop, because if the signal is always there, then when you press the play button the device will crash.

So, is there a component on the PCB that has that sort of behavior?

[pabouk]

I do not know how the ON/Play button is connected but the main part of the cricuit for turning the unit on should be a monostable multivibrator like for example SN74LV221A which will generate a pulse after connecting the power (+5V) of the USB. Then you will need a simple logic circuit which will combine the pulse with the button output and which will prevent generating the button press event when the USB is inserted while the unit is turned on. Depending on the actual circuit around the ON/Play button the extension circuit could be simpler.