Having trouble with LM2907 F/V converter

Thread Starter


Joined Feb 9, 2009
HI everyone

I have seen that a lot of people have experience with this chip and i was able to find a lot to help me out but now i'm kind of stuck and need advice.
I'm using the 8-pin LM2907N-8. Attahced is the data sheet and circuit.

I'm getting the Vo of just 3.23 max with Fin of 5khz. The lower values are fine (1v = 1khz, 2v = 2khz and 3v = 3khz) approx but not getting the 4v and 5v out.
Even changing the voltage input doesn't make a lot of difference.
Freq input is square wave 5v pk-pk. R1= 20k, C1= 10nF, R= 1k & C2 = 1uF.
I did tried according to the data sheet but it was giving funny readings (very less) but i'll try it again as see what it does.

Plz give any suggestions and advice on it.


Thread Starter


Joined Feb 9, 2009
I have increased the power supply but it was still the same. However i got what i needed on pg 16 (changing techometer gain curve or clamping the min output voltage).
Its working fine in this config but i'm having current issues (when chip connected). when i use a potential divider for bring it from +12v to +10v.

any ideas? why? and what should be done?


Joined Dec 20, 2007
I answered your questions on the other website.
Your "voltage divider" makes a very poor 10V regulated supply.