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ZR2ACJ > IDEA 22.09.03 18:58l 95 Lines 3837 Bytes #999 (0) @ WW
BID : 929_ZR2ACJ
Read: GUEST OE7FMI
Subj: Re:Old point/condenser to Electronic.
Path: DB0FHN<DB0RGB<DB0FSG<DB0GAP<DB0KFB<DB0CZ<HB9EAS<HB9AK<ZS6FB<ZS0DLD<
ZS6BJU<ZS6RO<ZS0ELD
Sent: 030921/1624Z @:ZS0ELD.ELD.ECP.ZAF.AF #:25382 [EAST LONDON] #:25382 Z:5247
From: ZR2ACJ@ZS0ELD.ELD.ECP.ZAF.AF
To : IDEA@WW
ZR2ACJ/TPK 1.82 Msg N§:929 Date:21-09-03 Time:15:06 SAST (-2HRS for Z)
Hi all, and thank's for reading.
Here is a simple conversion from point/condenser (in yester year motorcars)
to electronic switching.
Benefit,...reduces current load on point contact from about 2-3amps to as
low as 4 milliamps!.
Here is the circuit:
+ 13.8dc volts from car battery __ _High voltage
+ -----------------------------------------------\SW. / (Sparkplug)
| | / \
--- --- \ /
3k3 | | | | 25 ohm/20watt / \ (Existing car
1/2watt | | | | \ / coil.)
--- --- / \
| | ------------CB.-----
| |c c | |
| / ----- /---- |
---- -| -b--| \--b--| |
| \ \ ===== (Existing car condenser
\|/ 2N-3055 BU-208(a) ===== about 0.2--0.7 mf)
points |e |e |
/|\ | | |
| | | |
__ --------------------|----------------------
|
-----
---
-
The equivalents of the Power transister, "2N-3055" is as below:...
BD-315
BD-745b
BDW-51b
BD-317
BD-50
2N-5629
2N-3773
2SC-2608
Collector to Base = Max.100v
Collector to Emitter = 60v
Base to Emitter = 7v
Maximum Power = 115Watt
Current gain = 40
The equivalents of the High voltage Transistor, "BU-208(a)" is as below:...
BU-508(a)
BU-207(a)
BU-208(d)(Internal damper Diode)
BU-508(d) " " "
BU-800
2SD-1171 /2/3/4 or 5
2SC-2928
Collector to Base = Max. 1500v
Collector to Emitter Max. 1400v
Base to Emitter = 5v
Maximum Collector current = 5Amp
Maximum Power = 50Watt
Current gain = 5
The "a" on "BU-208(a)" for LOW RESISTANCE, because when the
Transister switches off...it must be off, not half off!.
The resister, 25 Ohm/20Watt can be made up with 4 off 100 Ohm/5Watt
resisters in parallel.(Ceramic resistors)
Last but not least...you can modify the contact (Points) area by replacing
it with a "555 Timer IC" in the Astable multivibrator mode,(Square wave)
output and use the unit to make a High-voltage power/burgular proof fence
around your valuables.
As you can see that the High-voltage Transistor can handle up to 5amp, and
the current at the contact breaker will be 4 Milliamps!.
Hope this is of any use.
Cheers and "Totsiens",
Andy ZR2ACJ.(East London - South Africa)
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