Parts:
P1 = 2.2K
R1 = 100K
R2 = 100K
R3 = 100K
R4 = 8.2K
R5 = 68R
R6 = 6.8K
R7 = 1K
R8 = 1K
R9 = 150R
C1 = 1uF-63V
C2 = 100uF-25V
C3 = 100uF-25V
C4 = 100uF-25V
C5 = 22uF-25V
Q1 = BC560
Q2 = BC550

Notes:

• Harmonic distortion is about 0.1% @ 1V RMS output (all frequencies).
• Maximum input voltage (level control cursor set at maximum) = 25mV RMS
• Maximum input voltage (level control cursor set at center position) = 200mV RMS
• Enclosing the circuit in a metal case is highly recommended.
• Simply connect the output of this device to the Aux input of your amplifier through screened cable and suitable connectors.
  

The ultrasonic position system uses ultrasonic transmitters/receivers to triangulate position of the robots used in GE423. Each of three transmitters uses a distinct frequencies: 23 kHz, 31 kHz, and 40 kHz. The 2812 DSP is used to measure signal timing and calculate position based on these values. The design of the electronics, as well as discussion of the software development is presented below.

1.0 Hardware

1.1 Ultrasonic Transmitters/Receivers

1.2 Transmit Circuit

A schematic of the transmit circuit looks like:

Images of the perf-boarded transmit circuits:

Details on the components of the transmit circuit can be found in the subsection below:

1.2.1 Frequency Generation

The transmit circuit take from the Massa Website looks like:

1.2.2 555 Timer Circuit

The documentation for the 555 timer can be found here. An a picture of how it is wired can be 


seen below:
Source:http://www.williamson-labs.com/480_555.htm
Using the handy calculator for Ra, Rb, and C found here, Ra=100k ohm, Rb=200k ohm, and C=2.2 mircoF.

1.2.3 Driver Signal Circuit

The 35 Vdc supply is manufactured by Ultravolt, part number 1/4Aa24-P30. This supply is actually a 0-250 Vdc supply that uses a potentiometer to control voltage output.. The transistor used is an IRF520 n-channel MOSFET.

1.3 Receive Circuit

A block diagram of the receive circuit can be seen below:

And a picture of the perf-boarded receive circuit can be seen below:

Details on the components of the receive circuit can be found in the subsection below:

1.3.1 Low Signal Amp Circuit

An instrumentation amplifier made by Analog Devices was used to amplify the low signal output of the ultrasonic receivers. The actual part used was the AD620, one is recquired for each receive channel. Analog has a nice tool here, to size the gain resistor, Rg. Based on experiments, a gain value of 33 was chosen, resulting in a Rg of 1.5k ohm. The AD620 was wired as follows:
Source:http://www.analog.com/images/Product_Descriptions/3888333375812882340AD620_fbs.gif

1.3.2 Comparator Circuit

The analog comparitor used was part number LM339. The volatage divdier was powered using +5 Vdc to creat the digital level output signal. The output from each instrumentation amplifier was wired to the "+" terminal, and the "-" was wired to 3 volts. The 3 Vdc signal was created from the +15 Vdc supply using a voltage divider. The output of the comparitor was wired to a 5 Vdc via a 3k resistor.

2.0 Software

The timing of the hardware interrupts from the 2811 is calculated, and from the times, position is calculated in the 2D plane using a combination of least squared fit and Jacobian iteration.

2.1 Matlab Triangulation Code

The first algorithm was developed using Matlab. This code can be found here. The algorithm is not stable for all input parameters, a good set of test conditions are:
[x,y]=blah(.010,.012,.012)
[x,y]=blah(.009,.014,.012)
[x,y]=blah(.011,.011,.011)
Note the highly descriptive function named blah

2.2 DSP C Code

The c code for the 2812 DSP is in the attached zip file. The code works as following:

1. Hardware interrupt pin get triggered
2. Record absolute clock time when pin transition occurs
3. Go back to step 1,and once all three pins have been triggered:
1. (only do this step the first time through the code) Assume robot stationary, acquire base transmit period for each frequency by averaging first 4 values, this step syncs the clocks of the transmitters to the robot
2. Calculate time from transmitter to robot for each frequency
3. Triangulate position of robot using least squared fit to data points
4. Wait for fixed amount of time, ignore hardware interrupts during this time because of the nature of the transmit signal
5. Go back to Step 1

3.0 Lessons Learned

1. A resistor was needed in parallel with the tuning potentiometer to give better resolution
2. A resistor was required in parallel with the US transmitter for the circuit to function because the transmitter is like a capacitor.

4.0 Acknowledgments

Various people and online resources aided in this project:

• GE423 Lab Instructor: Dan Block
• GE423 TAs: Dave Johnson, Daniel Herring
• My officemate: Steve Tschopp
• Misc. Consultation: Tim Cargol
• Misc Websites:
  • http://ourworld.compuserve.com/homepages/Bill_Bowden/555.htm
  • http://www.williamson-labs.com/480_555.htm
  • http://www.massa.com
  • http://www.digikey.com (source for datasheets)

Flip Flop LED

Flip flop circuit is a series of free runing multivibrator given the burden of LEDs on each side of the transition changes its output signal. Flip flop circuit with LEDs is quite simple, that is prepared with 2 units and 2 units of 2N3904 transistor circuit tank circuit composed by the RC circuit. 

LED indicators signal a change that is placed on each side of the flip flop will be lit in turn by the fire and extinguished the same as the charge and discharge capacitor. Flip flop circuit is quite simple as shown in the picture below.

Temperature and humidity sensors used are SHT75. This sensor is a chip that can measure temperature and humidity as well. The use of these sensors with consideration of its small size and reliability. The output of this sensor has the form of digital data in the chip because it has been there for a 14bit ADC. Temperature measurement range between -40-123,8 º C and humidity between 0-100% Rh. measurement accuracy reaches ± 0.3 per increase in 25 º C for temperature and ± 1.8% RH for humidity.
Here is a picture of temperature and humidity sensors SHT75:



The default measurement resolution of this sensor is 14 bits to 12 bits and temperature sensors for humidity sensors, can also use only 12 bit resolution and 8 bits.

Line Follower Robot Sensor Concept - Sensor line detector is used in line follower robot is usually based on the principle of light reflectionto distinguish the line with the background color. In the dark color of the light absorption is greater than that of white light reflected to the sensor becomes smaller.

Light used for the introduction of the line is usually visible light and infra-red. Sensors for visible light are commonly used are LDR (Light Depending Resistance), while for the infrared light is atransistor and photo diode (photodiode). Sensors placed at the bottom of the frame to hang the robot, so that its position can be located just above the track to be read.

The circuit schematic drawings Surround Audio Decoder and its components and how to make it ,Audio surround decoder circuit. Surround sound quality is the process of adding the audio source by increasing the number of speakers. This is done by producing audio multitracking in a way that can be issued on a multichannel speaker.

Basically surround adopt an existing stereo system. The system uses a two-speaker stereo is right speaker and left speaker. With two speakers will be three-dimensional effect of the sound issued. With the surround, which generated three-dimensional effect was more extensive than in stereo. This is because the surround speakers that use more than two pieces. In addition to supporting the three-dimensional effects, stereo field theory is also noteworthy to organize the arrangement of sounds based on the type of sound produced.

Surround effects can only be listened to speakers who have more than two channels. Surround is a technique commonly used in todays films that utilize multichannel speakers. Surround allows voice can move from side to side, is a moving side to side is to move from one speaker to another speaker. To create three-dimensional sound effects you can use a series of audio surround decoder.

See from above scheme may occur to you, certainly cheap enough to make this amplifier and quite easy to make. The above simple audio amplifier circuit using an IC as the main amplifier and accompanied by other components. IC used is S1513, which requires a supply voltage ranging from 1.5 volts to 6 volts. And only 0.1 W output power with 4 ohm impedance. For a list components can be seen below.

Part list

C1 = 100nF
C2 = 100uF

C3 = 3n3F

C4 = 1uF
C5 = 1uF
U1 = S1513

The CDI ignition circuit produces a spark from an ignition coil by discharging a capacitor across the primary of the coil. A 2uF capacitor is charged to about 340 volts and the discharge is controlled by an SCR.

A Schmitt trigger oscillator (74C14) and MOSFET (IRF510) are used to drive the low voltage side of a small (120/12 volt) power transformer and a voltage doubler arrangement is used on the high voltage side to increase the capacitor voltage to about 340 volts.

A similar Schmitt trigger oscillator is used to trigger the SCR about 4 times per second. The power supply is gated off during the discharge time so that the SCR will stop conducting and return to its blocking state. The diode connected from the 3904 to pin 9 of the 74C14 causes the power supply oscillator to stop during discharge time. The circuit draws only about 200 milliamps from a 12 volt source and delivers almost twice the normal energy of a conventional ignition circuit.

High voltage from the coil is about 10KV using a 3/8 inch spark gap at normal air temperature and pressure. Spark rate can be increased to possibly 10 Hertz without losing much spark intensity, but is limited by the low frequency power transformer and duty cycle of the oscillator. For faster spark rates, a higher frequency and lower impedance supply would be required. Note that the ignition coil is not grounded and presents a shock hazard on all of its terminals. Use CAUTION when operating the circuit.

An alternate method of connecting the coil is to ground the (-) terminal and relocate the capacitor between the cathode of the rectifier diode and the positive coil terminal. The SCR is then placed between ground and the +340 volt side of the capacitor. This reduces the shock hazard and is the usual configuration in automotive applications.