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THIS IS STILL A PROTOTYPE; NOT
TESTED OR WORKING!!!!!! TECHNICAL
HELP OR REVIEW APRECIATED
(I'M A POOR SOFTWARE ENGINEER...)
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Status:
11.01.2003 Tx and Rx are working with the 2 voltage
regulator. the switching circuit on the rx side is not commutting
as expected. Help needed!
26.01.2003 measure the current to correctly determine the values
of R for the bipolar transistor switch
I NEED YOUR HELP! I
f you can resolve this, feel free to contact
me, all ideas
are welcome: (read the principle before)
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Costs: as
found in Europe
- RX and Tx Aurel 433MHz
29€ and 9€. They need both a very stable
alimentation: 5volts +- 250mV
- 2 Voltage regulator, 7805 (+5V)
- Cycle computer, limit to 300km/h ($15)
- 1 Transistor 2N2222A and some resistors.
TOTAL: currently $53 approx $70 expected,
target below 100$
I can only work during the week-end, expect to have a runnable
device in 2-3 weeks. I will use a dremel electric motor to test
the accuracy of the final setup (both in remote, and in
"normal" mode to test linearity and response time).
Principle:
 |
| The cycle computer do not use a hall sensor, only a
switch that can be closed by a magnet. The RX ciruit part
must also simulate an electronic switch (close or open
the cycle computer input). To be convinced, you can
simulate the sensor and see the speed increase if you
close periodically (fast enough) the 2 wires of the cycle
computer. |
Datasheets:
Drawning:
RX part: Document in Powerpoint, feel free to
modify it, and send it back with suggestions ->CLICK
HERE
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Right now, I do not know:
- if I need a comparator
after the digital data output. -> it is integrated in
the receiver. Output is 0Volt OR 3,8Volts (dicrete
values)
- if I need an antenna. Range
test to be done and incocuity of device (no interferences
in PPM and PCM mode)
The transistor is not switching,
bad value of ib and rb, rc (11.01.2003)
- Rc
found for IC = IC1 = 10
mA and VCE = VCE1 = 1 V. lead to RC = (VCC-VCE1)/Ic1=
(1,53 -1)/0.01=> Rc= 50 Ohms - Rb
found for IB = IB1 = 100 µA . Vcde = 5
V. lead to Rb = (Vcde-Vbe)/ IB1,
Vbe=0.7V for Silicium Transistor
=> Rb=44KOhms
TX part: Document in Powerpoint, feel free to
modify it, and send it back with suggestions ->CLICK
HERE
Right now, I do not know:
- if I need in ?A? a separate
power source, (with this lot of ampere, we can destruct
the detector when it will be close by the magnet),
- if I need in ?B? something
for avoiding the noise when the mechanical switch will
close...(should create at least 400 on-off....) to test
if it modify the speed, the cycle computer should
integrate one already. Bad: it only send no relevant data
to the RX.
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Prototype:
When you create or try to reproduce this kit, please
validate each stage before continuing: in eg:
1. Test both voltage regulator, assure that they
deliver 5 volts +- 250mV
2. Test the TX and RX, simulate the on/off signal with a wire
connected to +5Volts, the Rx output go to a voltmeter
2. Do not connect the sensor, you can use 2 wires, one connected
to +5V, the other side to the data input of TX
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final version:
TODO
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gallery:
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