Help me provide -8V for pin 14 of MC1496

[epilot]

hello there,

i want to make a AM modulator using MC1496,
my problem is that the IC needs -8V for pin 14 and i don't know how provide the voltage for this pin,
regarding to the datasheet can anyone help me find a solution for this proble?
https://pdf1.alldatasheet.com/datasheet-pdf/view/12005/ONSEMI/MC1496.html

thanks for any help.

 

[Miguel Gaspar]

mc1496 uses

Tell me what voltage source do you have?

 

[epilot]

ewb mc1496

Tell me what voltage source do you have?

i use from 12V for supplying,

 

[Miguel Gaspar]

mc1496 application schematics

Ok you must use a Switching power supply to obtain -8 Volts.
You can use the 3524 switching regulator to obtain -8V
LM3524, SG3524, UC3524 etc.

 

[elbadry]

mc1496 single supply

You can run it from a single supply. there is no actual need for dual supply I think

 

[epilot]

mc1496 application note

thanks for inputs,

but can anyone direct me to a circuit for these kind of power supplies?

i have no idea about them, so please help me,

thanks again

 

[unkarc]

detail of mc1496

Hi,

Elbadry is right, there is a possibility to use a single polarity supply.

See Figs. 25 and 28 in Page 8 of the data sheet of this IC here:

https://www.onsemi.com/pub/Collateral/MC1496-D.PDF

The solution is to provide the correct bias currents (by resistive voltage dividers) to the base inputs of the Gilbert cell transistors. Because these inputs are the open bases of the transistors without any internal bias supply connection.

Notice the 1.3 kOhm-820 Ohm-1 kOhm voltage divider between +Vcc and the Ground. They provide the correct bias for the bases.

Notice also that that Pin 5 of the IC goes to the +Vcc via a 10 kOhm resistor in these two Figures, while in the split supply case it goes to Ground via a 6.8 kOhm.
Study Fig. 23 for the internal schematics too.
There is an application note here but of course you can find lots of other circuit in the web by searcing for it: https://www.onsemi.com/pub/Collateral/AN531-D.PDF

rgds
unkarc

 

[epilot]

mc1496 single supply modulator diagram

ok, thanks for all helps,

i'll do it with single supply,

but can some body let me know how can i find out if it works ok after making the circuit?

by the way i am i n doubt which kind of sine wave oscillators are good for this device?

Hi,

Elbadry is right, there is a possibility to use a single polarity supply.

See Figs. 25 and 28 in Page 8 of the data sheet of this IC here:

https://www.onsemi.com/pub/Collateral/MC1496-D.PDF

The solution is to provide the correct bias currents (by resistive voltage dividers) to the base inputs of the Gilbert cell transistors. Because these inputs are the open bases of the transistors without any internal bias supply connection.

Notice the 1.3 kOhm-820 Ohm-1 kOhm voltage divider between +Vcc and the Ground. They provide the correct bias for the bases.

Notice also that that Pin 5 of the IC goes to the +Vcc via a 10 kOhm resistor in these two Figures, while in the split supply case it goes to Ground via a 6.8 kOhm.
Study Fig. 23 for the internal schematics too.
There is an application note here but of course you can find lots of other circuit in the web by searcing for it: h**p://www.onsemi.com/pub/Collateral/AN531-D.PDF

rgds
unkarc

 

[unkarc]

Re: MC1496

Hi,

Depending on the carrier frequency you need to use, up to 25-26MHz you can check the quality of your AM modulator by a medium/short wave radio receiver tuned to the frequency in question and listening to it. Well if your frequency is higher than 26MHz, then you must search for a lab at some University near to you where an AM modulation measuring instrument/receiver can be found.

For the oscillator, this also depends on your frequency. Colpitts, Hartley, Clapp are all suitable I think.

unkarc

 

[epilot]

Re: MC1496

ok, thanks for all helps,

i'll do it with single supply,

but can some body let me know how can i find out if it works ok after making the circuit? yes i have an oscilloscope.

by the way i am in doubt which kind of sine wave oscillators are good for this device as carrier?

Hi,

Elbadry is right, there is a possibility to use a single polarity supply.

See Figs. 25 and 28 in Page 8 of the data sheet of this IC here:

https://www.onsemi.com/pub/Collateral/MC1496-D.PDF

The solution is to provide the correct bias currents (by resistive voltage dividers) to the base inputs of the Gilbert cell transistors. Because these inputs are the open bases of the transistors without any internal bias supply connection.

Notice the 1.3 kOhm-820 Ohm-1 kOhm voltage divider between +Vcc and the Ground. They provide the correct bias for the bases.

Notice also that that Pin 5 of the IC goes to the +Vcc via a 10 kOhm resistor in these two Figures, while in the split supply case it goes to Ground via a 6.8 kOhm.
Study Fig. 23 for the internal schematics too.
There is an application note here but of course you can find lots of other circuit in the web by searcing for it: h**p://www.onsemi.com/pub/Collateral/AN531-D.PDF

rgds
unkarc

 

[xxnononoxx]

Re: MC1496

Hi all,
Can help me with a design circuit?
the spec. r below or u can refer to this for more detail

under liquidgear

The circuit should be designed to obtain a frequency of 3.5KHz.

SPECIFICATIONS:
•Power supply to the circuit = 10V DC.
•The output of the circuit should be PWM (Pulse width modulated) waveform.
•The chopper frequency = 4kHz ±15%.
•The duty cycle should be manually variable from 0 to 100%.
•There circuit should have emergent stop function.
•The block diagram of the circuit is shown in Figure 1.
•The PWM waveform is shown in Figure 2.

DESIGN CONSIDERATIONS:
•The circuit should be designed using UC3524 to obtain the specified frequency and variable duty cycle.
•A MOSFET is used as the switch as shown in Figure 1 and the waveform as in Figure 2.
•After successful testing on resistive load, the circuit is then used to drive a DC motor and realize variable speed control.


Pls sent me the schematic diagram thank.


Email: xxnononoxx89(at)hotmail.com