Here's the current version of the complete Speedmachine circuit:
http://img221.exs.cx/img221/8633/spe...atic1074wr.jpg
The main sections are labeled in blue. The flasher oscillator is an LM555 connected as an astable multivibrator. It continuously generates an approx. 1/2 Hz 8 Volt square wave that is applied to the emitters of both 2N3904 transistors. Looking at the left signal circuit at the top of the diagram, the IRFZ34N MOSFET (Metal Oxide Semiconductor Field Effect Transistor) controls the current to the left side front and rear turn signal LED units. Under normal conditions the 2N3904 transistor is turned on, which biases the gate of the MOSFET high, so it conducts and the LEDs get power. The oscillator output has no effect as long as the 2N3904 is conducting.
Now when the left turn signal switch is closed, it brings the base of the 2N3904 low and it stops conducting. This allows the oscillator output to control the gate of the MOSFET, switching it on and off and thereby flashing the left turn signals. The right turn signal works the same way.
The hazard flasher switch clamps the bases of both 2N3904s low, turning the transistors off and applying the oscillator output to the gates of both MOSFETs, causing all four turn signal units to flash on and off in unison. The 1N914 diodes connected to the hazard switch isolate the left and right circuits from each other.
The VN0300L MOSFETS control the turn signal indicators on the handlebar unit. When the IRFZ34Ns are conducting and the turn signals are lit, the VN0300Ls and the indicators are turned off. When the turn signals turn off, the indicators turn on. This 180° phase shift is necessary because under normal conditions (no signalling) the turn signal LEDs are on steady, acting as daytime running lights and contributing to the visibility of the bike in traffic. The turn signal indicators will therefore be normally off and will only light when a turn is signalled or the hazard flasher is on. A small piezo beeper is connected to the drains of the two VN0300Ls through isolating diodes with a trimpot to adjust the volume. The beeper sounds when either left or right or both indicators flash. The beeper will go in the handlebar unit if there is enough room.
I described the battery voltage monitor in my previous msg. The power supply section consists of the battery, a low voltage cutoff (LVC) circuit, and three 7812 voltage regulators. Each regulator supplies approx. 300ma. which is well below the 1 Amp max. rating. Since the headlight/Warp Drive will be turned off only on rare occasions when I need to conserve battery power, I decided not to add a separate switch. Instead I will use the Hi-Off-Low-Off polyswitch that is built into the Nite Hawk Emitter headlight. More details on the LVC later.