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# VCO range 100KHz to 200KHz

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#### ceaser

vco 100khz

hi all

now i'm trying to desine a VCO has a range between 100KHz to 200KHz.

i tried to use the wien bridge osc.

but it gives me max freq of 20KHz because it use op-amp.

similarly 555 chip because it has two op-amp's in its two inputs.

i shouldn't use any freq dividers or multipliers.

just VCO sweeps from 100KHz to 200KHz.

can any one help me!

op amp vco 100khz

To design VCO operating in this range you can use part of the CD4046 ..
https://www.electronics-tutorials.com/devices/74hc4046.htm
A control voltage can be connected to pin 9, and output signal can be taken from pin 4 (see picture below) ..

The exact range and component values (R1, R2 and Cx) can be determined by extensive charts included in the above data sheet ..

Regards,
IanP

### ceaser

Points: 2
chemelec cd4046

thx alot IanP

Added after 4 hours 43 minutes:

Sorry guys

but now my instractor said

"no use of any chips you can use colbet or hartly tuned circuits "

but the problem of these circuits is the coil

we need coil of 70 mH

because the varying capasitors in the market are between 10&40 PF

so if there is no way to design this VCO without chips or op-amp's

i will make coil with large inductance

so any one know how to calculate the inductance using iron core

what i know is the inductance is a function of

No of turns,wire length,............etc

Use the AL value (from powdered iron core data sheet) and the formula(s) below to calculate the number of turns for a specific inductance.
Where:
N = Number of turns, L= inductance (µh), AL = inductance index ((µh) / 100 turns)
https://www.bytemark.com/products/ipcores.htm

Regards,
IanP

Points: 2

### ceaser

Points: 2
why don't you try:

rgds,
M

Points: 2