Sequential Timer Specs - doc00033
The circuit is a two stage sequential timer with auto reset. It
can turn a Solenoid On/Off after a Sequence of delays that are
preset. This is also a basic example of timer usage in
You can make very simple Timers with 555 also - Display
On Timer with 555
Sequence Of Operation -
- Power on the Circuit.
- If Start switch is pressed.
- Then after Timer Delay T1 Secs the Solenoid Operates
in Forward Direction.
- Next after Timer Delay T2 Secs the Power to Solenoid
is cut off.
- Timers are Reset.
- Circuit Ready for next press.
The Source design files for this project are here - Two
Stage Sequential Timer Docs
All Timers are 1 - 30 Secs Analog with Presets to adjust with a
screwdriver. The Switch, Solenoids and Power supply has to be
via terminal blocks or plug-jacks. The PCB may be upto six
Square Inches for standard DIP components but with SMD it may be
LED Annunciators -
RED LED - indicates battery needs charging, battery is dead.
will go off when battery has been charged.
YELLOW LED - indicates power is coming from adapter. will go off
if mains supply is off or adapter is not plugged.
GREEN LED - Indicates Start was pressed and process in on. will
go off when the 2 timers are done - reset and cycle is complete.
RED LED - Indicates solenoid is on. will go off when solenoid is
The LEDs can be grouped in two sets on PCB or enclosure as
specified. Specify if LEDs have to be on PCB to the PCB
designer or ask him for a connector arrangement for remote panel
Solenoid Specifications -
Volts - 12V, Current max - 500mA, surge - 1.2 Amps,
coil - > 30 ohms. Type Push-Pull.
solenoid specs changed so as to make circuit smaller. There in
no movement on reversal of polarity.
User End Inputs -
A provision for both START and STOP switches will be
present, you can omit the STOP. Power supply to circuit : 18V -
AC, 1.5 Amps, low voltage isolated, transformer or mains
adapter. quality of transformer will determine product safety !
Battery - 14.4 volt 1000 mAH Prismatic Li-Ion Battery
Have a look at this Interesting Project which will develop your
skill - Mikes
Optical Timer Counter
Method of work :
- The Circuit will be sent to you after you approve this
page of specs.
- The Circuit must be prototyped on breadboard at your end
- All troubleshooting help will be provided by email.
- You then need to make a PCB for the circuit and have it
built by vendor.
- The circuit and technologies in the circuit will be open
The PCB has to be tested to conform with the circuit, this has
to be Meticulous. The Circuit is for the Battery and Solenoid
Specified and will have to be modified if battery and solenoid
are different. D1 to D4 can be replaced by a 300V 3A Bridge
Rectifier Module. F1 fuse could be 2A - 3A Slow Blow depends on
Solenoid inrush current. Presets can be with some graduations if
possible for ease of adjustments. LED resistors can be a bit
lower if more brightness is required.
Then try these modifications if you have problems. In
del90005.pdf change C12 10pf to 68pf.
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