Transistor tester

[tsi431]

hi,,,im new in this site,,, i want to ask u about the way u read the No. of bins in the 2 ICs , is it different or the same?
is it like following..
IC1 IC2
5678 16 15 14 13 12 11 10 9
1234 1 2 3 4 5 6 7 8

 

[mixos1]

IC2 is correct but IC1 is:

8765
1234

You measure pins as the folowing image indicates. Also you can search the net for datasheet of the IC you are using.

View attachment 35072

 

[tsi431]

hi ,, thank u very much for reply... ,,the problem now is that i've only one led lighting not flashing....what do u think is wrong?

I would be very pleased for any help that you can give me about this circuit as I'm new to this site and I've not yet managed to get this one to work so far.

 

[mixos1]

I can't know what's is wrong. I suggest you to test the connections very-very carefully.

 

[tsi431]

do u think i damaged the 555 ic?

 

[mixos1]

You can check if 555 is ok by measuring the output pin 3. It must has a 12Hz signal. To do that you must have access to an oscilloscope or a digital multimeter that measures frequency. Alternativally you can replace 555 to be sure it's ok. Keep in mind that the most common problems are at the connections. Double or triple check them in different moments in a day so your mind is clear. Also make sure you really understand the connections reading the schematic and there are not confusions.

 

[mozikluv1]

hi there,

it seems a few members have a problem having this project work. my xperience when i first built this project cost me 2 damage CD4027. the most common problem is the damage CMOS.

another member was asking if the series/parallel signal diode (IN4148) is presented correctl in the schem. yes, it should be connected as presented in the schem. remember that what the author had in mind when he designed this circuit that it can be used to test transistors in-circuit, so he has to employ such circuit configuration. am not trying to be the spokesman of the author but let me try to explain why this circuit is used in the design:

looking at the schem you will see that the 2 sets of series IN4148 are connected in series with the D.U.T. via its Collector terminal. it works this way, they allow only a current path thru the DUT as long as the transistor is fully saturated. thus insufficient current would flow thru parallel resistances resulting that 1 or both LED would be dark or unlit.

i hope this would make things clear.

in fact i have made revisions to this circuit using only 1 ic (CD4093) a quad 2-input NAND Schmitt Trigger in place of the 555 & 4027, but still using the same basic set up on the testing side, and it work just fine. i could check diodes, SCRs & transistors and it could also show the transistor type.

also pls remember that the output at pin 14 & 15 are at opposite of its other state. when 14 is high 15 is low which causes both LED to flash alternately. so if only 1 LED lights up continously, no alternate flashing, it means one of the output is not functioning. so what would be your logical conclusion.

 

[mixos1]

Yesterday I received a report from a user, read it:

I have an update for you regarding the transistor tester as I was having a few problems in getting it to work well it works now as a few modifications have been added such as connecting pin 8 of the 4027 to ground and then linking pins 3 and 9 of the 4027 together it then works.

once again many thanks mike it is a good site.

keep up the good work from kev Tellyaddict42[no-spam]aol.com .

Anyone that don't succed with this transistor tester can try this solution and post comments here so i will make any suggested corrections on schematic.

Thanks

 

[steven2]

there is a simple transister tester i biult from a kit as handy as it is as a handy dandy peace of test gear , ive decided to biuld some myself , i have the decade counter tester, 4001 ic tester, 4011 ic tester, 555 and 556 ic tester and scr tester and reverse mode transformer tester . and 1458 ic tester and the 741 ic tester, and n channel mosfet tester, hv flyback transformer output tester, thats just some of it. [email protected]

 

[saqib]

hi
i read out ur very good suggestions.iam also working o this project
i want to have some more details of this project(theory)
that what is happening internaly and what the way it works ?
on what conditions the flip flop turns how diodes behave etc
so any links ....or message..
i will be very much grate full to all of you people
and this is a grate site
keep it up

 

[hearmewell]

Hi there, im a newbie..is there anyone still doing this project ? can anyone send me the picture of the complete project and the ic's datasheet.. and is there anything that i have to ensure before starting the project ? ???

 

[mozikluv1]

hi hearmewell,

nice user name you've got.

all the problems encountered in building this project has been addressed in this forum. the datasheet you were asking is also here. browse thru all the Q & A here.

good luck

 

[hearmewell]

i guess so .. thanks.

 

[jilandgig]

Hello, I just built your transistor checker because I could not find one to buy. We manufacture our own tube gear and other electronics. After I built the unit with no transistor connected I get a solid LED2. What I understood was that both lights should flash. What should the unit do with no connection to and transistor? I have double checked the wiring and it's correct. All wiring is point to point, no board. Please let me know your thoughts.

 

[MP1]

Have you read this thread from the beginning to see what others have commented on it? There were some needed changes posted by someone who built it.

MP

 

[steven2]

there is an in circuit transistor tester , i posted to the forum before, its simple to biuld and i biult mine from a kit and all the details are there to so check it out.

 

[MP1]

steven, do you remember where you posted it? post a link. I tried the search fuinction and it would not come up. I do not think it will be found otherwise.

MP

 

[audioguru2]

If you want the flip-flop to alternately toggle its output, then it must be clocked. The datasheet shows that the clock is pin 13, but the project's schematic has it grounded. So pin 3 of the 555 should connect to IC2's pin 13, not to pin 12. Pin 12 is IC2's reset, which should be connected to ground.
Also, the circuit will work better with a power supply bypass capacitor of about 100uF, connected from positive to ground.

 

[steven2]

mp cannot up load the file but it where i said it is in elctronics lab but if anyone has problems finding it ill re photo it and email it again

 

[steven2]

you will find my in circuit transistor tester post on page 9 of electronics projects/design ideas.