Vermes
Advanced Member level 4
This version of C-ESR meter was based on that project: **broken link removed**.
Some things were changed in this project:
- new PCB, mixed assembly THT+SMD
- switch on bistable relay was added
- external power supply socket
- LCD backlight at operation from power supply
- more stable operation
Schematic of the switch:
Bistable relay with two coils was applied to this project. The relay needs voltage only in the moment of switching, both locations are stable, so you can switch the contactors and you have to fed voltage each time. Two coils make the control easier (you need only two microswitches which realize turning on and off). When operating from external power supply, the switch is skipped and backlight is on. Due to the consumption of backlight current (80mA), you can resign from battery operation.
Everything fit on a one sided PCB with dimensions of 86x46mm. Transistor N-MOS, TL431, 78L05 and ICL7660 are in through-hole elements, other IC in SMD version. There is the drawing of the board.
All through-hole elements are visible on the top side of the PCB:
SMD components:
Load for the PIC can be downloaded from: **broken link removed**.
Picture of the inside of the meter:
Orange cube is the bistable relay, which was mounted outside the PCB.
Link to original thread (useful attachment) - **broken link removed**