NPN transistor problem

Thread Starter


Joined Feb 23, 2012
Please don't laugh, but a transistor in circuit is measured at its legs using AC scale and not DC. Many thanks-- this is important. (The schematic says like 7.4 volts)

Sorry, did not post a title so re-posting.
Do you measure an NPN transistor, in circuit, using AC or DC volts...schematic says on one leg (7.4 V) Many thanks....

The schematic is located at
and is Q7 & Q8. Would Q9 be AC or DC?
Last edited by a moderator:


Joined Nov 30, 2010
Welcome to AAC.

Now about that schematic...if I could see it I might know what you are talking about. Can you post the schematic here by using the "Go Advanced" button? The best format is .png

You can make a drawing with the Paint program in Windows computers. You can make a pencil drawing and scan it, then upload it. There are several ways to get a drawing to appear with your question.

Next item, what is your question?


Joined Nov 30, 2010
It's usually measured as DC but it depends on what the transistor is doing.

This answer has become seperated from its thread. I have reported it to the moderators so they can find its home and put it where it belongs.
Last edited:


Joined Oct 29, 2009
It also helps if you choose a subject line that makes at least some sense. Casey is meaningless other than maybe to you.


Joined Mar 24, 2008
Well, it didn't go exactly as planned, but I merged all the posts into one post.

Casey, Welcome to AAC.

Instead of splattering the forum with a bunch of posts all about the same project, it is better to focus on one thread. It is how it is done here.

You will find you can attach your images here in the form of attachments <wince>.

To attach a document or picture to a post

Click "Go Advanced" at the bottom of your post,

One of several options will pop up,

Click "Manage Attachments" much further at the bottom of your post,

To upload a file from your computer click "Browse", then select the file.

Schematics should be .gif or .png format, pictures should be .jpg. .jpg formats will fuzz out schematics, and should not be used for that purpose.


Joined Dec 20, 2007
The RCA radio is more than 50 years old and should be buried.
The voltages shown on the schematic are DC voltages when the radio is not playing. The voltages of Q9 are shown to be B= +7.4V, E= +6.8V and C= +72V.


Joined Mar 24, 2008
Looks like I did it again. Some threads were left behind from the last merge, so I did it again.