Nigel Goodwin said:
What are you wanting to switch?.
Well to sum up, I'm building my own DIY CD PLAYER.
There are seveal modules in it :
1- The controller board made of the PIC18F452. This board manages the data from/to the the DRIVE (a philips CDPRO2 mechanism), data to be displayed on a LCD, IR data.
2- A dac made of 2 TDA1541A in //, with a tube output stage
3. A PSU board with several voltages :
* 5V for the controller board, the DAC as well as the decoder of the drive
* -21V for the DAC
* 235 V /6.3V for the output stage.
*9V for the drive (mechanism)
The issue is to manage the start of the modules in a good sequence as the CDP is switched off /on
When ON :
1- First the controler board (+5V)
2- Then after a short delay, the DAC (+5V, -21V, 6.3V, 235V)
3- Then the decoder of the drive (+5V)
4- At least, the +9V of drive.
A minimu m of 400ms has to be respected between each modules.
When OFF, take the sequence upside down.
I could manage the delay by inserting RC cells.
But it costs to much and it is less interesting than managing the delay by the PIC. On top of that, I could quickly changed the delay (400ms to 300, 500,...) just by amending the program.
That's why, I attend to control several relays between the PSU board and the other modules. They would switched on/off to enable the flow of current.
Hope it's clear, my english is not as good as expected