[ARCHIVE] An old project from Thomas Schattat from Germany.
- Adaptable to other single-cylinder bikes.
- Tuning of the advance curve (255 points).
- Software source available (.ASM).
- 7.500RPM max
- Compact & economic.
- Don’t need a alternator.
- Need a battery
Designed for a TT600R, this ignition is generating the High Voltage needed to load the capacitor.
It doesn’t need a AC alternator.
“DC-DC converter control circuit” switch on/off the primary coil of L1 transformer at 25KHz.
The transformer has a ratio of around 10, so the secondary gives 10 times the primary voltage.
The secondary voltage is half rectified by D3. There is around 160Vcc that charges C2 capacitor.
The energy in the spark is E=0.5 * C * U*U (joules,farad,volts)
At 12.000 rpm, with a scope we measure that the time available to charge a 1uF capacitor is 5ms
To go from 0 to 320volts in 5ms, it needs an Energy of:
E=0.5 * C * U*U
E=0.5 x 1 x 10-6 x 3202
E=0.5 x 1 x 10-6 x 102400
E=0.05 joules = 50mJ
25 to 100millijoules are enough to get a spark.
0.05J for 5ms => Then for 1 second (1000ms):
1000ms/5ms x 0.05j = 10 joules
To convert in Watt: 1 joule = 1 Ws (watt second) so 1 joule during 1 second = 1 watt
The dividing bridge R17 + R14 fixes the potential at AIN0 entry to 2.9volts.
D5,D6 protect the entry from over-voltage.
The positive pulse of the signal goes to gnd by D4
The negative pulse pull down the voltage at AIN0 pin, this is detected by the processor, which calculates the necessary delay then provide a zero volt pulse to Q1 transistor.
The transistor turns ON and blocks the inverter circuit MC34063 so that it does not produce any more High Voltage.
Q1 triggers T2 SCR Gate at the same time. T2 then discharges the preloaded C2 capacitor into the ignition coil.
The coil amplifies this tension by approximately 100 and puts out 20.000volts to the spark plug which generates a spark.
Over 8000 RPM, the ignition is off (line 54)
Under 588 RPM, the ignition is off (line 56)
Between the maximum and the minimum RPM, the ATMEL processor measures the duration between 2 pickup pulses in 400us steps to know the speed engine in RPM.
According to the speed, the processor searches the related position in a 256 values map. (line 59)
The processor find the delay value (lines 105 to 116).
Then the proc. waits for this delay [in 100us steps].
At the end of the delay, a 400us length pulse is sent to the thyristor.(line 90)
Duration of the spark:
The duration of the spark cannot be adjust on a CDI, it depend of the capacitor value and the coil value.
This SCR’s gate pulse duration can be change line 90, but without impact on the spark duration.
You can change directly the values from the table (lines 105 to 116)
And don’t forget:
The timing delays in the assembler program are based on a pickup coil mounted about 58° before TDC, different bikes may have different positions here!
Watch out! This is an old project exposed to be inspirational. You can have a hard time to update it for recent AVR-ASM compilers….
|PCB||Circuit imprimé.PNG||Eagle V4.11|
|Cuivre & composants.PDF||Cuivre & composants.BRD|
Compiled with http://www.batronix.com/
You can remove the line “INCLUDE 89C2051.mc” if your compiler doesn’t need it but make sure that the ports I used are known by the assembler, otherwise you’ll get a different error.
Also the syntax may not completely be accepted by your compiler and you may have to tweak a bit.
L1: naked transformer available at Conrad Electronics
order #:51 66 43
Primary coil : 25 turns 0.5mm wire
secondary coil: 160 to 180 turns 0,15mm wire
Important : Leave a little air-gap between the 2 metal parts by slipping a bit of paper for example.
Another How-To build the transformer.
– This ignition on a BMW F650 Enduro: