4G LTE 4 Pole Inter Digital Filter for Digital TV

This is the design of 4G LTE filter for Digital TV . As we know some of 4G LTE transmit frequency , overlapping with Digital TV reception frequency on 698 - 806 MHz. So, this 4 Pole Inter digital Filter made from aluminium plate and copper rod. You can experiment with it , I am not tested yet, for another design you can follow from VK3UM software online at VK3UM.com

LM 335 Temperature Sensor Circuit

Temperature Control Circuit :

Image Courtesy Texas Instrument

The temperature controller circuit using +5 V voltage source from I/O slot at IBM PC/XT/AT.

IC LM 335 from Texas Instrument have the ability to detect temperature from ranging -40 celcius degree until 100 celcius degree.

This LM 335 from Texas Instrument , is zener diode which have the linear coefficient voltage increment related with increment of temperature with formula :

Vz = + 10 mV/ C (celcius degree) , with current opeartion between 400 uA until 5 mA.

On the circuit Resistor 2.2 K use for limit the current flow to cathode pin from LM 335 which is output of LM 335 sensor temperature.

On circuit Resistance of R is 2.2 K , and at 25 Celcius degree from data sheet of LM 335 , voltage at LM 335 will be 2.982 Volt , so current flow can be calculate :

Vcc = + 5 V

Voltage at 25 Celcius on LM 335 = 2.982 V

Voltage at Resistor R 2.2K is = 2.018 V

Current flow through LM 335 and R will be = 2.018 V / 2.2 K = 0.9 mA

This 0.9 mA current at LM 335 still on at range of sensor LM 335, and then the output cathode pin of LM 335 sensor from Texas Instrument connect to input 0 of ADC0809 Analog and Digital convertion data from Texas Instrument at pin 26.

Temperature Sensor LM 335 from Texas Instrument

Temperature Sensor using IC LM 335 from Texas Instrument. LM 335 is Zener Diode which sensitive of temperature change in it surrounding , which is reverse bias on it breakdown area with output :

Vz = [10 mV/Kelvin] …..........[2-1]

Because there is gap different 273 degree between Kelvin and Celcius , so the output in Celcius for LM 335 from Texas Instrument will be :

Vz = 2.73 Volt + [ 10 mV/Celcius] T.........[2-2]

where T is in Celcius Degree

IC LM 335 from Texas Instrument have temperature range between -40 celcius degree – 100 celcius degree

I use LM 335 in Plastic Package TO-92 , another package for LM 335 is SOIC 

Images courtesy Texas Instrument

Another IC temperature sensors from Texas Instrument are LM135, LM135A with TO-46 package, LM235 and LM235A in TO-92 package and LM 335 and LM 335A in SOIC package.

From this writing, I want to discuss about Simulation control system with IBM PC 

XT/AT for Temperature, heater, and pump using LM 335 as sensor, PIO 8255, ADC 0809 , MOC  from motorolla , and TRIAC .

This control system operate with software with QBasic , and I will write the schematic diagram, implementation, and software design.

For more data about LM335/LM335A . please visit data from Texas Instrument , here

4G LTE Bandstop Antenna UHF Filter 703 MHz - 803 MHz

As from 4G LTE Band spectrum, we can see that at LTE Band 44 , allocation frequency of 4G LTE at 703 MHz-803 MHz. And this spectrum frequency , overlapping with digital TV spectrum. As we know, digital tv spectrum frequency at band 703 MHz - 803 MHz, with bandwith 100 MHz.
So the center frequency will be :

Center Frequency 703 - 803 MHz = 753 MHz

I use Bandstop filter calculator refer to http://www.wa4dsy.net/filter/filterdesign.html

 After we input the parameter of center frequency 753 MHz , and bandwith 100 MHz at calculator, then click compute parts as the menu on calculator, then we get the result of 3 filter design with 2 circuit , butterworth, bessel, and chebyshev.

The component values of  3 design filter, for butterworth, bessel, and chebyshev are :

 You can choose one of three offering design and choose one of two circuit for your implementation.
The output chart graph of filter design are :

3 Pole Bandpass Filter for uhf digital tv 470-800 MHz

This 3 pole bandpass filter using https://wetnet.net/rf_design/3pole.main.cgi  design calculator online.
this bandpass filter is butterworth filter and intended to filter digital tv bandwith 470MHz to 800 MHz , and only this signal will detected after antenna.

Parameter of filter :
Band Frequency 470 - 800 MHz
Center Frequency = 635 MHz
Bandwith = 400 MHz
Impedance = 50 ohm

Input this parameter to online filter calculator above :

 Click Submit , and the result :

L1,L3 : 0.008763 uH ( 8,763 nH)
L2      : 0.039789 uH (39.789nH)

C1,C3 : 0,000008 uF ( 8 pF)
C2      : 0,000001753 uF (1,753 pF)

We must determine for Inductor L1,L2,L3 the coil diameter, coil length and number of turn of coil.
Using online calculator from  http://www.qsl.net/in3otd/indcalc.html we can determine diameter, length and number of turn coil.
For L1,L3 :

L = 0,00876 uH , coil diameter will be  d : 0,01 m  , Coil length will be l  : 0.01 m and number of turns , n : 1,1355

And for L2 :

L = 0,0396 uH , coil diameter will be d : 0,0259 m , coil length will be l : 0,01 m and number of turns n : 1,1355

The most important thing of build filter is the connection between component should be as close as possible, for avoiding wild capacitance that will generate noise, and the ground area of PCB should be good and wide.
On the next article, I will posting the implementation of this filter.