Test data with proof of functional design
4.2 Operation of electronic dog collar
To make transformer function, first the input voltage must be in ac form. So to make dc voltage
to ac voltage an inverter is require. In this design project, transistor (BJT) is use as inverter
(oscillator). Figure below shown that simple concept how BJT been use as oscillator.
74 Imagine L1 is primary coil in transformer. When Vdc is apply current from battery is going
though L2 not L1 due to saturation mode (off) of BJT, Q1. When Voltage L2 reach to certain
level BJT will become cutoff mode (on) then the current will flow from battery to L1 coil.
Reminder, when L2 is conducting, L1 is going to discharge. Figure below shown that the voltage
waveform at L1 coil.
Figure 4.11: Waveform output 1
f = 5000Hz when Battery voltage = 2.7V
Table below shown that the result of Primary voltage,Vp (voltage at L1 coil).
Table 4.1 Primary voltage
Battery Voltage, V Primary rms voltage, V
3.0 5.50
2.7 5.21
2.6 5.21
75 In this design project, the BJT only can function in two mode only which is saturation and cutoff
mode this is because base-collector junction and base-emitter junction is always in same bias
(forward-forward, backward-backward). Changing the value of resistor does not change the BJT
to active mode; the only changing is BJT on-off switching time (frequency of transformer).
When the inverter (oscillator) part is solved then transformer can apply to step-up voltage. In
this design project a 50 turn ratio of transformer is used
Figure below shows the circuit diagram consisting BJT and transformer.
Figure 4.12: Circuit consisting BJT and transformer
The secondary voltage waveform is same as primary voltage waveform the only different is the
magnitude of the waveform. Figure below shown that the secondary voltage waveform:
76 f = 5000Hz when Battery voltage = 2.7V
Table below shown that the result of Secondary Voltage,Vs
Table 4.2: Secondary voltage
Battery Voltage,V Primary rms Voltage,V Secondary rms Voltage, V
3.0 5.50 270.81
2.7 5.21 239.48
2.6 5.17 230.41
(Vs dc = 0) f = 5000Hz when Battery voltage is 2.7V
From the table, since the secondary voltage is not high enough and also in ac form so a 2 time
multiplier is going to use. Figure below shown that the final circuit diagram
77 Figure below shown that the waveform of output voltage,Vo
Figure 4.15: Output waveform of the tasser circuit
f = 5000Hz when Battery voltage = 2.7V
Table below shown that the output voltage at different battery voltage level
Table 4.3: Output voltage at different battery voltage level
Battery voltage, V Vo rms, V Vo dc,V
3.0 23.19 995
2.7 15.12 660
2.6 14.29 610
78 4.2.1 Why Vo rms is so low compare to Vo dc?
Multiplier is one type of rectifier so that all ac voltage converts to dc voltage. Theoretically Vo
rms is zero (ignore) due to capacitor because capacitor filter the ac voltage.
4.2.2 How to measure output voltage
Seem the output voltage is so high that is no way direct measure from the output using
multimeter so voltage divided method is chosen. Two type of resistor are chosen which is 1.5M
ohm, 10% and 51K ohm, 10%. Two pair load are make which is 1.5M ohm- 1.5M ohm pair and
1.5M ohm-51K ohm pair. Using Multimeter, set Vdc to measure the output voltage. Result
shown in table below (battery voltage = 3V)
Table 4.4: Output voltage measurements result
Load R1,ohm R2,ohm V(R2),V Vo,V
1.5M ohm- 1.5M ohm 1.5M 1.5M 495.0 Vo=2V(R2) =990 1.5M ohm- 51K ohm 1.5M 51K 34.0 Vo=29.41 V(R2) =1000 Mean of Vo= 995V
The result above also testing by oscilloscope and the Vo is approximate 990V. About the Vo rms
79 4.2.2.1 Ideal operation
In ideal operation, Vp= battery voltage
= 3V Vs= 50 Vp = 150V Vo=2Vs = 300V Percentage of error = [(995 – 300)/ 300] X 100% = 231.67%
The percentage of error is too big due to:
1) In ideal operation the initial value of coil is assume zero
2) The error come from instrument
3) The tolerant value of resister
4) In ideal operation, a lot of assumption is make
In this project, the electronic dog collar can generate two different voltage there is three way to do it , method
1) Control input voltage using resistor, Rin (prefer) 2) Add or deduce diode-capacitor pair in multiplier 3) Control output voltage using voltage divided method 4) Using feed back system to control Rin
Each method has advantage and disadvantage, method
1) Can get any different of output voltage (<1000V) but it will change the frequency of BJT and transformer.
80 3) Can get any different of output (< 1000V) but also make a lot of power loss
4) Can get any different of output (<1000V) but have to choose proper respond time
Figure below shows the circuit diagram with Rin
Figure 4.16: Rin application
81 Table 4.5: Output voltage with different Rin value
The Rin value just stop at 8.2 ohm because when Rin value up to 16 ohm the output voltage
almost become zero and that is no point for generate low voltage. From the table above, the
conclusion is Rin increase Vo decrease
4.2.2.2 Current drawn from battery when open circuit and short circuit
Battery life time is depend to the how circuit consume current at load side(output). The table
82 Table 4.6: Current drawn from battery with different Rin value
Io= open circuit current, Is= short circuit current
From the table above, the conclusion is
1) battery voltage high the more current draw from battery
83 4.2.2.3 Relation between R (Rin + R1) and frequency
Figure 4.17: R (Rin + R1) and frequency relation
Observe from oscilloscope, value R increase frequency also increase. Mention before when
frequency too low transformer cannot be drive because voltage is direct proportional to
frequency. When frequency is too high there is no enough time for charging in multiplier, it will
affect the output voltage. The project is function when R (Rin + R1) is in 470 to 478.2 ohm
(observed from oscilloscope).
Why R affect frequency
To make it easy, assume voltage at L2 coil reach certain value the BJT switch will trigger.
84 When di become small due to R (Rin + R1), dt also become small (dt = f). So when R increase
frequency also increase.
Modifying electronic dog collar
Modifying is needed so that to improve the circuit becomes more safety and more users
friendly. The figure below shown that some modifying in this project
Figure 4.18: Modified electronic dog collar circuit
From the figure above a LED is added shown in ‘A’, the purpose for adding LED is let user know
that the electronic dog collar is in ready-mode, ready for training. Another modifying is add one
resistor at the output side shown in ‘B’, the purpose for adding resistor is to discharge the
charge store inside the capacitor, this is important and also for safety purpose because when
dog trainer take out dog collar from dog and user miss-press the remote control button it will
85 4.3 Testing on wireless communication
4.3.1 Testing RF-Module
A testing RF- Receiver circuit is build to test the receive signal. The schematic of the testing circuit is shown in figure 4.19 below.
Figure 4.19: Schematic of testing circuit for receiver.
There are 8 LED as indicator of the receive data is connected in port B of PIC16f877A. Once data is receive by the receiver, the receive data will move to show in port B. There are 8 LED because the data receive is in 8 bit and each LED represent each bit of the data. Hence the Data receive is in binary form can be convert manually to base 10 number.
86 4.3.2 Determine how the receiver is interfere by other transmitter with same frequency.
Due to the receiver circuit shown in figure 3.11 will be interfere whenever there is other transmitter with same frequency transmitting data, the testing circuit shown in figure 4.19 is used to determine the how the other transmitter will interfere the receiver when two transmitter is transmitting. The experiment is conduct as explain below:
Procedure:
1. One of the transmitters is programmed to send a digit 80, which is 01010000 in binary continuously.
2. The other transmitter is programmed to send digit 55, which is 00110111 in binary continuously.
3. The data receive by the testing receiver circuit is being recorded. 4. Table below shows the result obtain from the receiver.
Table 4.7: results for testing inference
Data receive by the receiver in binary form Data receive convert to base 10
10001001 137 11100101 229 01010011 83 10010011 147 00010101 21 00100101 37 11100100 228 00101001 41 00101011 43 Analysis
From the result obtain above, it can be prove that the interference does not stop the receiver to receive data. However, it hardly receive a correct data transmit form either of the transmitter which is either 80 or 55.
87 Discussion
The transmitter transmits data bit by bit from the less significant bit to most significant bit. Same thing goes to the receiver where the first bit it receives is the less significant bit and the last bit receives is the most significant bit. Figure 4.20 show the data was transmitted and received bit by bit.
Figure 4.20 Data is Transmit and Receive Bit by Bit
Hence, the 1 byte data receive by the receiver is not exactly the 1 byte data from a single transmitter if there is more than one transmitter transmitting data. The 8 bit data receive is come separately from the different transmitter which causes the failure for the receiver to receive data. Figure 4.21 illustrate the error occur when there is interference.
From Transmitter
88 Figure 4.21: illustrate the error occur when there is interference
However, this type of error cannot solve by either software or hardware. As long as the frequencies of the transmitters are the same, it will interfere with the receiving process. If two transmitters are used, when the transmitter is not transmitting data, the supply source to the transmitter has to be cut off to prevent this type of interference. The method use to cut off the source is discussed in section.
Conclusion:
Although the interference discussed in this section cannot by avoid by either software or hardware but the error data will not execute the program. Which mean that even though there is interference, with the 2 byte sending method, the electronic dog collar will not shock the dog when error data was received.
4.3.3 Determine The Range of The Wireless Remote Control
Another experiment is conducted to test the range of the RF remote control range. This experiment is conducted in SKTM block C, Makmal Electronic Asas. Three condition is being tested. These conditions are:
89 1) Transmitter and receiver without antenna,
2) Transmitter and receiver with antenna but the receiver is left in the room while the transmitter is outside the room.
3) Transmitter and receiver with antenna. Both the transmitter and receiver are tested in an open surrounding.
Test Result
Table 4.7: Experimental result of the range of the RF remote control in different condition
Condition Outcome
1 Receive Range less than 5 meters
2 Receive range about 25 meters
3 Receive range about 35 meters
Conclusion:
Seem the dog training is run in an open air surrounding, the range of 35 meters is more than enough for using this electronic dog collar for training purpose.
90 Chapter 5