HP5386A Backlight modification




Frequency counter HP5386A is a good instrument but it has a stupid disadvantage, the LCD no has backlight.
Below you can see how I managed to add some white LEDs, enough light to read easily on the LCD screen. All LEDs are suplied with +18,5V through a FET electronic switch because HP5386A no have 220V main switch and the front panel switch is only for standby/wake up. FET transistor can be any medium power N channel type.



SMD LEDs are installed at both ends of LCD (final version has 11 pcs LEDs because PSU voltage is not enough)
General view of LCD board
FET switch and power supply connection
Schematic diagram version 1.1
HP5386A ready to use (in reality the light is better)








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