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MINI

-PROJECT

43

11/2002

Elektor Electronics

ply voltage. Because the circuit is powered
from an asymmetric power supply, a coupling
capacitor is present at the input. This capac-
itor is always charged by R1 and R10 to pre-
vent any unwanted sound effects when the
signal source is plugged in. The coupling
capacitor is followed by an additional protec-
tion network, guarding against high peak
voltages. This network consists of two diodes
and a resistor.

For practical reasons, an inverting topol-

ogy was purposely selected for the adjustable
amplifier stages IC1a and IC1d. By using the
inverting inputs, the load on the potential
divider for the virtual ground (R27/R28) is
smaller, allowing higher resistance values
and consequently a lower total current con-
sumption.

If, for the moment, we limit the description

to the left channel only, we can establish that

few mA, the level adapter can sim-
ply be powered from a 9-V battery;
that makes it pleasantly universally
deployable.

Control circuit

If the circuit were only required to
attenuate, then we could have made
it easy for ourselves and a simple
passive voltage divider would have
sufficed. But in this case we also
wanted to amplify and, in addition,
we would also like a tidy circuit in
which the input and output-imped-
ance are not affected by the position
of the potentiometers.

That is why we decided to go for a

relatively ‘mature’ design. Each
channel consists of an input buffer

and an adjustable amplifier stage.
There is a single indicator common
to both channels. In order to power
the opamps symmetrically from a 9-
V battery, a virtual ground point has
been created with voltage divider
R27/R28/C11. 

Figure 1

shows the

complete schematic.

The indicator will be described

later, we will first take a look at the
buffer and amplifier stage.

The function of the input buffers

IC1c and IC1b is to provide a con-
stant load for the attached signal
source. The values are such that the
input impedance is fixed at the well-
known standard value of 47 k

Ω

. The

opamps are connected as voltage fol-
lowers, while resistors R3 and R12
bias them to half of the power sup-

6

7

1

IC2.B

4

5

2

IC2.A

10

11

13

IC2.D

8

9

14

IC2.C

R23

10k

R19

1k8

R20

1k8

P2

100k

3

1

2

R21

47k

R22

47k

D5

5V6

0W4

+9V

R25

820

Ω

R24

6k8

R26

100

Ω

D6

C7

47

µ

25V

C8

220

µ

25V

+9V

2

3

1

IC1.A

9

10

8

IC1.C

R7

1 M

R8

100

Ω

R5

4k7

R4

4k7

R2

1k

R1

270k

R3

56k

R9

100k

R27

47k

R28

47k

R6

1k

C1

4

µ

7

63V

C2

47p

47k

1

3

2

C3

4

µ

7

63V

D2

1N4148

D1

1N4148

+9V

13

12

14

IC1.D

6

5

7

IC1.B

R16

1 M

R17

100

Ω

R14

4k7

R13

4k7

R11

1k

R10

270k

R12

56k

R18

100k

R15

1k

C4

4

µ

7

63V

C5

47p

47k

4

6

5

C6

4

µ

7

63V

D4

1N4148

D3

1N4148

+9V

C11

100

µ

10V

C12

220

µ

25V

BT1

9V

S1

C10

100n

C9

100n

IC2

12

3

IC1

11

4

+9V

020189 - 11

L

L

R

R

IC1 = TS924IN

IC2 = LM339

lin.

lin.

P1.B

P1.A

P2: 200mV...  1V(RMS)

Figure 1. The level adapter actually consists of two separate circuits: the adjustment section and an overdrive indicator.

1

2

3

4

5

6

P1

Содержание EPROM

Страница 1: ......

Страница 2: ...style plug that can be inserted in an EPROM socket The length of the umbilical cord is limited to prevent a too high capaci tive load on the data and address bus of the target system or timing proble...

Страница 3: ...voltage to the Vpp pin on the device The level of the programming voltage depends on the EPROM type used and lies between 12 5 V and 21 V At the same time the EPROM sup ply voltage at the Vcc pin is r...

Страница 4: ...ctronics 11 2002 IDENTIFICATION 024066 TYPE GAL16V8 PINS Pin assignment for input signals EPVP 8 Detection of 5V supply EPVPP 3 Low active detection of VPP 12V EPOE 1 Input for OE from EPROM socket EP...

Страница 5: ...s This IC is necessary while the emulator is in Blank mode when it is exptected to supply the value FF at all times dur ing a read command The GAL arranges for the driver to be acti vated in the direc...

Страница 6: ...CS VPP OE Data Data out unknown WR CS RD G DIR EPROM RAM BUFFER Data in unknown 024066 15 Figure 5 Signals in Normal mode C E L E K T O R 0 2 4 0 6 6 1 C1 C2 C3 C4 D1 D2 D3 D4 D5 IC1 IC2 IC3 IC4 IC5...

Страница 7: ...upply pin of the EPROM After all the voltage at this pin may become 6 V during programming which is not a healthy level for the ICs in the emulator If you do want to employ this voltage measures shoul...

Страница 8: ...object since the propagation speed of the waves and the rate of horizontal deflection time base were known This is how R A D A R came about an acronym that soon turned into an everyday word Subsequent...

Страница 9: ...car comes nearer and then decreases as the car trav els past you This effect is also noticeable in F1 Grand Prix races when the cars roar past the camera This phenomenon works the other way round as...

Страница 10: ...problem for the detector is the signal to noise ratio which doesn t get any better with Schottky diodes In this section the sen sitivity can also be improved through the use of aerials Whilst the fir...

Страница 11: ...dars the circuits are less sensitive to interference signals the frequency of the jamming signal therefore has to be as close as possible to that of the speed camera and every device has its own frequ...

Страница 12: ...ocols used can come in three different varieties In Europe the most common protocol is the ISO standard All of these protocols rely on serial data transfer but the Vehicle Diagnostics Adapter Interfac...

Страница 13: ...aud and does not offer a handshaking option for the RS232 interface In addition it is only able to communicate using the 10 4 kHz ISO 9141 Protocol This stan dard is the most common used by the majori...

Страница 14: ...to the driver s seat The shape and pinouts of the 16 pin connector has already been described in the previ ous article Card Diagnosis Systems Elektor Electronics October 2002 The circuit described her...

Страница 15: ...hreshold voltage to around 4 V instead of the standard 2 5 V for a CMOS input The effect of this is to improve noise immunity on the input and the stage gain speeds up signal transition times For the...

Страница 16: ...should be about one diode drop 0 4 to 0 6 V higher than the voltage measured at the TxD pin In the circuit diagram TxD is assumed as 9 3 V which then gives 8 9 V after the voltage drop across D6 Shoul...

Страница 17: ...1 Assuming that the interface is correctly connected you should see the four red LEDs light up and the following message will appear on the screen ELM323 v1 0 This gives the version number of the micr...

Страница 18: ...ng the installation paths For the device driver you will need the EZ USB Development Kit which you have USB Driver Programming 2 writing your own device driver By M M ller and C Ehmer In the previous...

Страница 19: ...ctly cheap The solution proposed here is to use freely already installed and used in Part 1 of this series Setup information Windows always needs an INF file for installing a device driver Such a file...

Страница 20: ...device driver Start Visual C Studio select Open Working Area from the File menu and open the file named MICROCONTROLLER 32 Elektor Electronics 11 2002 Figure 3 Testing the device driver in BinTerm Ta...

Страница 21: ...aths in the compiler and linker options must be modified accordingly If the code cannot be generated without errors or war nings the environment has not been configured properly Under C it is nearly i...

Страница 22: ...to MYSYS SYS Copy the modified INF file and EZUSB SYS to a diskette You have now produced a driver diskette for a Cypress IC with the VID and PID numbers you have defined Connect the USB device having...

Страница 23: ...The solution was found in the S88 bus This controller interface which is quite busy collecting return data via the track when PC control is used has precious little to do in stand alone operation Tha...

Страница 24: ...and large this circuit does the same thing as the simple version An 8 position switch is used once again to select the controller and even the pushbutton switch is still present although here it is hi...

Страница 25: ...tand This trick is performed by two 4 bit binary full adders type 4008 whose operation we will not attempt to explain here Suffice it to say that we have here is a sort of primordial computer IC The 8...

Страница 26: ...a switch before it can be programmed The super deluxe controller address pro grammer does not have these disadvantages and it allows the addresses of up to eight GENERALINTEREST 39 11 2002 Elektor El...

Страница 27: ...ard Figure 4 is designed to have K2 K3 and K4 fitted on the back side solder side so the board with the rotary switch and display can be fitted directly behind a front panel see Figure 5 EEDTS Pro key...

Страница 28: ...re shown in Figure 8 and Figure 9 The first one uses a relay with two electrically isolated make or changeover contacts If all of the contacts of the available relay are already being used the circuit...

Страница 29: ...put sensi tivities and limited output signal lev els can be mitigated by preceding the relevant line input with the con trol circuit that is described here The signal levels of 2 V that modern CD or D...

Страница 30: ...ecided to go for a relatively mature design Each channel consists of an input buffer and an adjustable amplifier stage There is a single indicator common to both channels In order to power the opamps...

Страница 31: ...d R20 so that both the negative as well as the positive half of the signal voltage is monitored Because the zener current is set to a really small value of only 1 mA the voltage drop across D5 is only...

Страница 32: ...o construction should not be hurried The terminals for the inputs and outputs are nicely grouped on one side of the PCB while on the oppo site side two SIL headers can be found for the connections to...

Страница 33: ...hears a cry When a cry is detected and persists for a given time it will dial out a pre pro grammed number typically the par ents mobile There is no need to answer the call a glimpse at the mobile s...

Страница 34: ...rence voltage REF The other input AIN0 is connected to the AF signal CMP and when this signal rises above the reference voltage the com parator output will switch and gen erate an interrupt in the mic...

Страница 35: ...adapter unit supplying 9 to 12 V provides power for the baby monitor A pro tection diode D5 ensures that reversing the power supply leads cannot damage the input C19 acts as a smoothing capacitor to...

Страница 36: ...uipped with a Pulse Width Modulated PWM output and this can do the job just as well This output has a resolution of 8 bits with a clock frequency of 19 6 kHz fCK 510 The dual sine waves are produced b...

Страница 37: ...e number is zero do not press S1 at all after tapping in the digit press S2 to enter it and move on to the next digit of the number Carry on until the complete number is entered and then a long press...

Страница 38: ...s order number 53 06 89 33 that has its existing window removed You can of course change the dimensions for use with a differ ent type of exposure box The parts The frames are made from two pieces of...

Страница 39: ...out of a piece of aluminium Figure 2 shows all the relevant dimensions the hole on the left fits over the stay peg This could have been a round hole but then this should have had the exact size of the...

Страница 40: ...s been found the sliders should be moved tightly against the pins The wing nuts are then tightened and the align ment is complete The protective films on the PCB should be removed in a dark room The t...

Страница 41: ...aterial as the anode and there recombine with the returning electrons and with oxygen from the air to form water This is known collectively as the membrane electrode assembly MEA Researchers at Motoro...

Страница 42: ...he output of the reformer Using the multi layer ceramic technology researchers have demonstrated an integrated vapouriser and miniature methanol steam reformer and a separate chemical heater three of...

Страница 43: ...chosen to use white LEDs instead of a halogen lamp Contrary to popular belief the efficiency of a white light LED is not much better than a low power tungsten bulb and in fact worse than higher watta...

Страница 44: ...lector arrange ment For the power source a lithium ion rechargeable battery has been cho sen These cells are more expensive than NiCds but offer a number of advantages A NiCd cell of the same capacity...

Страница 45: ...ister ADRES is given by Rearranging VBATT is measured every 100 ms to regulate the output power The microcontroller uses this battery voltage measurement to point to a stored look up table for one of...

Страница 46: ...that stock them Charge indication An important design feature of the torch is that the user should never be left unexpectedly in the dark It is GENERALINTEREST 61 11 2002 Elektor Electronics 012019 T1...

Страница 47: ...harge left in the cell the torch will function for 5 hrs at brightness level 4 or more than 12 hrs at level 5 so you should never be left completely in the dark The battery and coil The battery specif...

Страница 48: ...ount components and LEDs onto the boards The coil is the only conven tionally packaged component and should be soldered to the component side of the PCB The two PCBs are then soldered together at righ...

Страница 49: ...atterns and character sets You will also find many useful links leading to application examples and other sources of information Another address for information on this controller connection details o...

Страница 50: ...ience in this area may want to start off at an extensive description containing lots of photographs of an LCD connected to a printer cable on the Build your own printer cable LCD display 9 webpage pro...

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