cool New Member Feb 20, 2004 #1 I have followed the data sheet of LM567 to build up a circuit to encode 10kHz input singal, but it doesn't work........ :cry: I used R1=2k, C1=47nF, 0.1uF and 0.01uF at pin 1 and pin 2. It seems no center frequency appeard, all input signals with different frequencies have the similar value of output voltage.......... What can I do??? Did I make any mistake??? Please help me.... :wink:
I have followed the data sheet of LM567 to build up a circuit to encode 10kHz input singal, but it doesn't work........ :cry: I used R1=2k, C1=47nF, 0.1uF and 0.01uF at pin 1 and pin 2. It seems no center frequency appeard, all input signals with different frequencies have the similar value of output voltage.......... What can I do??? Did I make any mistake??? Please help me.... :wink:
R Russlk New Member Feb 20, 2004 #2 The bandwidth is way too wide. Try 2000 uF at pin 2. For 10% bandwidth, 0.1 = 1070*sqrt(vin/Fo/C2) (9.3*10^-5)^2 = vin/Fo/C2 Let vin =0.2 & Fo = 10^4 then 87*10^-10 = .2/10^4/C2 C2 = .2*10^-4/.87*10^-8 = .23 *10^4 uF
The bandwidth is way too wide. Try 2000 uF at pin 2. For 10% bandwidth, 0.1 = 1070*sqrt(vin/Fo/C2) (9.3*10^-5)^2 = vin/Fo/C2 Let vin =0.2 & Fo = 10^4 then 87*10^-10 = .2/10^4/C2 C2 = .2*10^-4/.87*10^-8 = .23 *10^4 uF
cool New Member Feb 21, 2004 #3 o, thanks~ but what is Vi? is it the supply voltage of the circuit of the encoder?? :roll:
R Russlk New Member Feb 21, 2004 #4 Vin is the amplitude of the signal input to the 567. I don't know why it affects the bandwidth.