 |
 |
 |
 |
 |
| delabs
Technologies |
Search | Contact | Service | Discuss |
Power supply with battery backup for DMM - del20010This is a simple charger circuit which will work for a light load like a DMM, the Battery can be a sealed maintenance free battery of 9V-2AH or better. The circuit will work best if the Unit is powered on many times daily on regular use, else battery will drain down.The 555 Astable is used to generate a AC signal from which a negative voltage is generated, A 79L05 which is a low power TO92 equivalent of 7905 a negative -5 volts regulator is used as -5 volts load is less. A TO220 7805 is used for the +5V supply. To view the circuit below, Click the Link of PNG or PDF and view the Circuit, PNG can be Scrolled with Mouse and PDF can be Viewed-Zoomed in the Browsers with Acrobat plugin. The Javascript and Images must be enabled in your Browser. |
| PNG-Schematic
PDF-Circuit DSN-Source |
| Power supply with battery backup for DMM - del20010 |
| PNG
Image Can be
Scrolled by Drag-Drop Left-Click-Mouse, PDF Requires Adobe
Acrobat Reader Plugin. |
Data sheets and info useful to study and build this circuit. LM555 - Timer, NE555 Timer/Oscillator Data sheet, 555 timer, 555 Timer Tutorials Voltage Regulators, Rechargeable Batteries and Chargers |