tacho

[mechtronics]

i have just wired up this and i am getting an output voltage of 2.17 volts without any frequency connected. i assume this is wrong as i connected another of the same chip and it was reading zero which should be right for no frequency input.??? i assume that the chip is faulty?? any1 know??

 

[jackorocko]

I would assume the chips is bad too. Do you only have two of the same chips? Is there a test circuit in the datasheet that you could use to test the IC?

 

[mechtronics]

no i have 5 of the same chips 4 are reading zero and 1 is reading 2.17 volts i think one of them is faulty.
when i connect a frequancy the 100 k should vary the output voltage for me.

 

[davenn]

no i have 5 of the same chips 4 are reading zero and 1 is reading 2.17 volts i think one of them is faulty.
when i connect a frequancy the 100 k should vary the output voltage for me.

have all 5 chips been tested in the same board ? that is... you are using an IC socket to be able to swap the chips for testing ?

if so then pretty conclusive that the chip has been damaged... its VERY rare to have purchased a faulty chip.
If the chips are all on separate boards then maybe you have made a wiring fault on the board with the faulty chip

Dave

 

[mechtronics]

no all on the same board im using a bread board to test the circuit before i solder it permanently onto stripboard all the chips have been tested on the same board too. so i think it is a faulty chip myself?

 

[davenn]

no all on the same board im using a bread board to test the circuit before i solder it permanently onto stripboard all the chips have been tested on the same board too. so i think it is a faulty chip myself?

yup sounds like it and as said in my previous post its VERY rare for it to be a manufacturing faulty device. More likely you damaged it with either static or incorrect placement into the board

cheers
Dave

 

[mechtronics]

ya i think i damaged it myself by accident!!!!

 

[davenn]

ya i think i damaged it myself by accident!!!!

it happens, if you are going to be playing with electronics on a regular basis you should really buy an anti-static mat for your workbench and a the wrist strap that goes with it.
Make sure the mat is grounded appropriately
It will save you a lot of grief in the future, specially if you start playing with even more static sensitive IC's etc

cheers
Dave

 

[mechtronics]

ya i had that in mind for quite a long time now still havent got around to buying it!!!!