Understanding Transistor Data and Replacement

If, for some reason, you can't get an exact replacement for the transistor that you want to replace, you can refer to one of the transistor substitution guides or book, and try to identify a "near replacement". Beware, however. A substitution guide will sometimes list a replacement for your part, even though the two parts are not very similar. The most commonly used transistor substitution guides is the Philips ECG semiconductors Master Replacement Guide. Selecting the right transistor parameters or specifications for the equipment you repair will avoid callbacks from customers. Callbacks or repeated repairs due to wrong transistor substitution will cost you extra money and a waste of time.

Some important transistor parameters are:

Maximum collector-to-base voltage (VCBO) ? The replacement part should have a VCBO rating equal to or higher than the original.

Maximum collector-to-emitter voltage (VCEO) ? The replacement part should have a VCEO rating equal to or higher than the original.

Maximum emitter-to-base voltage (VEBO) ? The replacement part should have a VEBO rating equal to or greater than the original.

Maximum collector current (IC) ? The replacement part should be able to handle as much (or more) collector current as the original.

Power dissipation (PD Watts) ? The replacement part should be able to dissipate as much (or more) power as the original part.

Gain (hFE) ? The replacement should have a gain equal to or better than the original and it should be as close to the original specification as possible.

Gain-bandwidth (fT) ? the replacement should have a transition frequency equal to or faster than the original and it should be as close to the original specification as possible.

Below is a table of application requirement and important specification that you can use for guidelines when comes to transistor substitution.

Application Requirement and Important Specifications

1. General purpose low level amplifier and switching transistors. Spec- hFE, IC (max), fT, VCEO

2. Power switching applications. Spec- VCEO, VCBO, hFE, IC (max), PD (max)

3. Low level IF/RF amplification. Spec- IC (max), fT, VCEO

4. Audio amplification. Spec- IC (max), PD (max), hFE, VCEO

5. High voltage transistors. Spec- VCEO, VCBO, IC (max), fT

Remember, the replacement transistor should not run hot and if problem still persist, try another replacement number or get the original number if possible. Do not overlook that the surrounding components also may caused the transistor to run hot even if original number is used.

Jestine Yong is a electronic repairer and writer. For more information about electronic repair please visit his website at http://www.noahtec.com

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Rep. Jack Franks (D-Woodstock) votes to recommend the impeachment of Illinois Gov. Rod Blagojevich to the House during an Illinois House Impeachment Committee hearing Thursday, Jan. 8, 2009, in Springfield, Ill. The committee voted unanimously to recommend impeachment putting the matter before the full house.  (AP Photo/Seth Perlman)AP - A key panel unanimously recommended impeachment for Gov. Rod Blagojevich on Thursday, setting up a vote that could make him the first governor to face such fate in Illinois' sordid political history. Blagojevich should lose his job for abusing power, mismanaging government and committing possible criminal acts, including federal allegations he tried to sell off a U.S. Senate seat, the special committee concluded.



Egyptian President Hosni Mubarak, right, hugs his French counterpart Nicolas Sarkozy at the end of a press conference on Tuesday Jan. 6, 2009 in Sharm el-Sheik, Egypt. Sarkozy said Wednesday Jan. 7, 2009 that Israel and the Palestinian Authority have accepted an Egyptian-French plan for Gaza.   (AP Photo/Eric Feferberg/Pool)AP - The U.N. Security Council approved a resolution Thursday night calling for an immediate and durable cease-fire between Hamas militants and Israeli forces in Gaza. The U.S. abstained from the 14-0 vote.



President-elect Barack Obama speaks about the economy at George Mason University in Fairfax, Va.,  Thursday, Jan. 8, 2009. (AP Photo/Charles Dharapak)AP - President-elect Barack Obama's proposed tax cuts ran into opposition Thursday from senators in his own party who said they wouldn't do much to stimulate the economy or create jobs. Senators from both parties agreed that Congress should do something to stimulate the economy. But Democratic senators emerging from a private meeting of the Senate Finance Committee criticized business and individual tax cuts in Obama's stimulus plan.



U.S. General David Petraeus, the commander overseeing military operations in Iraq and Afghanistan, talks during a conference in Rome December 9, 2008. (Tony Gentile/Reuters)AP - U.S. policy to win in Afghanistan must recognize the poor nation's limitations and its neighborhood, especially its intertwined relationship with U.S. terrorism-fighting ally Pakistan, the top U.S. military commander in the region said Thursday.



Vice President Dick Cheney pauses during an interview with the Associated Press at the White House in Washington Thursday, Jan. 8, 2009. (AP Photo/Ron Edmonds)AP - Vice President Dick Cheney said Thursday that he sees no reason for President George W. Bush to pre-emptively pardon anyone at the CIA involved in harsh interrogations of suspected terrorists. "I don't have any reason to believe that anybody in the agency did anything illegal," he said.



Directors of the BART transit agency listen to public comments on Thursday, Jan. 8, 2009, in Oakland, Calif. Speakers criticized the agency for its handling of a New Year’s Days incident involving a BART police officer who shot and killed unarmed 22-year-old Oscar Grant. (AP Photo/Noah Berger)AP - In grainy cell-phone videos played over and over on the Internet, police officers force an unarmed black man to the ground and hold him face-down on a crowded train platform. Suddenly one of the officers draws his gun and fatally shoots the man in the back — then looks up.



AP - An anti-tax group will consider new legal action after a California appeals court tossed out a lawsuit that sought to block tax increases passed by Democrats in the state Legislature, the group said Thursday.

The east side apartment building where Bernard Madoff remains under house arrest is seen Thursday, Jan. 8, 2009, in New York. Prosecutors said Thursday that investigators found 100 signed checks worth $173 million in Bernard Madoff's office desk that he was ready to send out to his closest family and friends at the time of his arrest last month. (AP Photo/ Louis Lanzano)AP - Prosecutors said Thursday that investigators found 100 signed checks worth $173 million in Bernard Madoff's office desk that he was ready to send out to his closest family and friends at the time of his arrest last month in what is alleged to be largest financial fraud in history.



AP - A funeral home might be a place for eternal rest, but police say an Arkansas man saw an opportunity to build a methamphetamine lab undisturbed by the living. There was just one problem — the funeral home was across the street from the sheriff's office.

Florida's Tim Tebow (15) throws a pass over Oklahoma's Auston English (33) during the third quarter of the BCS Championship NCAA college football game in Miami, Thursday, Jan. 8, 2009. (AP Photo/Mark Humphrey)AP - Tim Tebow took over for Florida and the top-ranked Gators grabbed a 14-7 lead over No. 2 Oklahoma after three quarters at the BCS national championship game Thursday night.



Israeli soldiers take their positions during Israel's offensive in the Gaza Strip January 8, 2009, in this picture released by Israel's Defence Forces (IDF). Israel is bent on halting Hamas rocket fire on its southern towns. Prime Minister Ehud Olmert said the goal that 'quiet will reign supreme' in the area had not been achieved. A decision on further military action 'is still ahead of us', he said. More than a dozen rockets hit southern Israel on Thursday. (Doron Keren/IDF/Handout/Reuters)Reuters - The U.N. Security Council called for an immediate ceasefire in the Gaza Strip but Israeli warplanes launched intermittent attacks on Friday.



President-elect Barack Obama at a news conference in Chicago, December 7, 2008. (Jeff Haynes/Reuters)Reuters - President-elect Barack Obama warned on Thursday the U.S. economy could stay mired in recession for years without bold action and he urged lawmakers to work day and night to pass a massive stimulus plan.



People taking the Long Island Foreclosure Tour arrive at a foreclosed home for sale in New Hyde Park, New York in this May 17, 2008 file photo. Citigroup could soon agree to principles that would let troubled borrowers save their homes through bankruptcy, sources familiar with the talks said on Thursday, while industry groups are easing their opposition to the plan. (Shannon Stapleton/Reuters)Reuters - Financial giant Citigroup Inc will support a proposal in Congress to rewrite U.S. bankruptcy law to help troubled mortgage borrowers avoid foreclosure, Chief Executive Vikram Pandit said on Thursday.



Illinois Governor Rod Blagojevich gestures as he announces former Illinois Attorney General Roland Burris as his choice to fill the vacant U.S. Senate seat of President-elect Barack Obama during a news conference in Chicago, Illinois December 30, 2008. (Frank Polich/Reuters)Reuters - A legislative committee on Thursday recommended the impeachment of Illinois Gov. Rod Blagojevich, citing widespread abuse of power including allegations he tried to sell the U.S. Senate seat vacated by President-elect Barack Obama.



Usama al-Kini, Al Qaeda's operations chief in Pakistan, is pictured in this undated FBI Most Wanted photograph. Al-Kini, also known as Fahid Mohammed Ally Msalam, and a top aide are believed to be dead, a U.S. counterterrorism official said on January 8, 2009, in what appeared to be the latest results of a campaign targeting the militant group's leadership. Operations chief al-Kini was thought responsible for attacks, including the bombing of a Marriott hotel in Islamabad that killed 55 people in September, and an unsuccessful attempt to kill former Pakistani Prime Minister Benazir Bhutto, who was later assassinated in a separate attack, the official said. (FBI/Handout/Reuters)Reuters - Al Qaeda's operations chief in Pakistan and a top aide are believed to be dead, a U.S. counterterrorism official said on Thursday, in what appeared to be the latest results of a campaign targeting the militant group's leadership.



Reuters - Some friends of accused swindler Bernard Madoff considered him a "warm and charming" man, and one of his alleged victims praised him just before his death in 2005, Fox Business Network reported on Thursday.

Virginia Governor Tim Kaine (L) delivers remarks after being announced as the new Democratic National Committee chairman by U.S. President-elect Barack Obama in Washington, January 8, 2009. (Jim Young/Reuters)Reuters - President-elect Barack Obama named Tim Kaine as head of the Democratic Party on Thursday, rewarding an early supporter with a high-profile political post even as he continues to serve as Virginia governor.



A man works near a pressure gauge at a district heating plant in Skopje January 8, 2009. (Ognen Teofilovski/Reuters)Reuters - Europe on Friday looked for a swift restoration of gas supplies, after striking a deal with Moscow on monitoring gas shipments via Ukraine that have been halted by a rancorous pricing dispute with Kiev.



US Secretary of State Condoleezza Rice speaks to an unidentified aide during a Security Council meeting at the United Nations. The UN Security Council voted to call for an AFP - The UN Security Council voted to call for an "immediate, durable" ceasefire in the Gaza Strip leading to the "full withdrawal" of Israeli forces, but the United States abstained.



A man carries firewood in the suburbs of Sofia, Bulgaria. Hopes for a quick resumption of Russian gas supplies to Europe were rising Friday after Russia agreed on the terms for the deployment of monitors in Ukraine.(AFP/Dimitar Dilkoff)AFP - Hopes for a quick resumption of Russian gas supplies to Europe were rising Friday after Russia agreed on the terms for the deployment of monitors in Ukraine.




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