MD-82
Flight Crew Air Transport Pilot (ATP)
Flight Crew Total 19500
Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Flight Crew Returned To Departure Airport; General Declared Emergency
Aircraft
Passing about 3;000 FT [in climb] I noticed a slight acrid (electrical) smell. Simultaneously; the First Officer then reported he saw a puff of smoke about 8-10 inches in diameter (light grey color) in the vicinity of the hydraulic pump switches and could also smell smoke. The smell increased in the next few seconds; however; there was no visible smoke after the initial puff of smoke. An emergency was declared and we requested vectors back to [departure airport]. I notified the flight attendants of the emergency. Aircraft was landed overweight at about 134;600 LBS at approximately 135 KTS. The smoke smelled electrical and even though it had dissipated; it was still noticeable after gate arrival. Responding fire equipment evaluated the aircraft for hot spots immediately after landing and after parking at the gate. No hot spots were identified. The cause of the smoke in the cockpit was identified by maintenance to be related to the TCAS display.
[Narrative 2 provided no additional information.]
An MD-82 flight crew experienced electrical smoke in the cockpit on initial climb.  They declared an emergency and returned to departure airport; where the smoke was reportedly traced to the TCAS unit.