Hi Jay_Diddy_B,
Can you please make some corrections to your schematic.
It is saying 4016 and 4053 as a fet switch...
Can you please put the pin numbers in the schematic for the 4016 or 4053?
Your output from the 555 wil not be RR, the components for the negatif supply rail wil load the 555 to mutch.
Use a transistor/fet buffer.
The 555 oscilator is NOT 50%/50%, it nead some extra components for that, take a look @ the data sheet for that.
Keep up the good work! :-)
Kind regarts,
Blackdog
The schematic is an LTspice model of the real schematic so the pin numbers are not shown. There is a real schematic in this thread with the pin numbers.
https://www.eevblog.com/forum/projects/esr-meter-adapter-design-and-construction/msg341177/#msg341177The switch is the 74HC4053. The switches in the HC4053 are around 140 Ohms. They are in series with a resistor of 470 + 1600 + 200 ohms, the switch only make up 6% of the total resistance.
The advantage of the 74HC4053, over using 4016 or 4066 switches is that I don't need an oscillator with complementary outputs. The inverter is inside the 74HC4053.
The 74HC4053 is considerably faster than the CD4053, but is a lower voltage part.
The 555 is not configured in the normal way. The output is used to drive the RC network. In this configuration to the duty cycle is very close to 50%. It is supposed to be 50% in this configuration.
The 555 output does not need to be rail-to-rail. The analog switches in the source make it rail-to-rail. The CMOS version of the 555 would be better, but there is no LTsice model for the 555C.
@oldway
The 2F divided by 2 with a F/F will give an exact 50% duty-cycle. I would probably use that technique if was building a bench meter. But I was building a small adpter.
The LTC6990 timer IC can also be used to provide an exact 50% duty cycle. There is a Frequency divider inside this chip. It has a single output, so an inverter is required.
Total power consumption of the circuit is less than 10mA, so there is no need to added any transistor buffers.
I did post the LTspice model if you want to play with this design.
There are many ways to do this, some is personal choice, some decisions are driven by the parts that you have. The fun is giving building your circuits and testing them.
Regards,
Jay_Diddy_B