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Electronics => Electronics => Topic started by: hazzer123 on January 30, 2008, 03:29:19 PM

Title: 7805 Regulator Voltage out Dropping
Post by: hazzer123 on January 30, 2008, 03:29:19 PM
I have a KA7805A voltage regulator and i am placing 12V of p.d. across the Vin and GND pins. This is well below the max input voltage of 40V.
The Vout pin gives a nice steady roughly 5.05V when connected to my motor driver board. All the electronics work fine.

When i attach the Vout and GND to both my motor driver board and my main MCU board, which i send the power to down the 4Wire ICD cable (+5v,GND,SCL,SDA), the Vout pin becomes 2.6V.

The is hardly any current through the voltage regulator ( it is rated at 1Amp max). All it is powering is 2 PICs, a couple of LEDs and a Sharp IR. The voltage regulator doesn't noticably heat up.

Any ideas on what could be happening and how to fix it?

Thanks
Title: Re: 7805 Regulator Voltage out Dropping
Post by: hazzer123 on February 01, 2008, 11:40:26 AM
Got another voltage regulator today, replaced the old one, and it works.

Just to let you know.
Title: Re: 7805 Regulator Voltage out Dropping
Post by: HDL_CinC_Dragon on February 01, 2008, 11:57:30 AM
Try making another proto circuit using just like 4 or 5 LEDs and have the supposed broken VReg to power the 5 LEDs in parallel. See if perhaps that vreg is still usable for things.