i have a problem with my circuit.
i am using a 12 volt motor bike battery
when i connect up the circuit, . i am getting a pulse but the transistor is staying on any ideas
Hi ,
try to put a 1 to 10 Kohm resistor from the Basis to Ground ofthe driver transistor.
Then it should work.
hi i have connect up 1k to 10 k resistor from the base off the transistor to ground but the transistor is staying on
Have you measured if the transistor is broken or not?
What is the "low state" voltage output from your "555" driver circuit.
It must go lower than 0.6V or the transistor will conduct.
If the output is higher than 0.6V you could try adding a 330R resistor from the base to ground.
Another thing. A regular 555 IC is to weak to directly feed a powerful but low HFE 2N3055 transistor.
You should switch the bipolar transistor to a low Rdson mosfet. A much better solution.
One last point. Have you measured the frequency coming from the 555?
If it is set to high (>1Khz) you will have problems when using a slow big 2N3055 transistor.
It simply doesn't turn of in time. The only good solution in this case is to use a faster transistor, e.g mosfet.
the low state out put of the 555 timer is 0.0v until the sensor is blocked and then it goes up to 12v
i do not know how to messure the frequency ????
By an oscilloscope or frequency counter
ne 555 wil never go to 0 volt saturation.
take an dvm . aoutput to groeund . if voltage is over 0,55 volt = the transistor will conduct alltime.
If from NE555 voms out at lowes polt 0,5-1,2 volt , then use an 1n914 /41440 (4007) in serie from transitors-base to ic ( also this current limiting resistor aswell the rbe (that setfan talked about ist)
Pese
what do you mean by taken a dvm
when i place the black probe on negative off the battery and the red one before entering 555 timer, on pin 2 and i get a reading off 0.12.
when i place the red probe on to the output off the 555 timer , after the 200ohms 1 wattresistor i get 9.45 volts
http://www.uoguelph.ca/~antoon/gadgets/555/555.html
someting wrong in your 555 circuit, pin 6 can connect to 12V?
so what would be the best circuit
Do you want to make optical trigerred timer circuit or "schmit trigger"
for pulse motor control?
this motor is bedini or newman's motor or normal motor?
i am looking for a circuit to fire a 2N3055 transistor,as to fire the coil, when the light of the sensor is blocked. i think the wave coming out from the sensor is a square wave so i do not need a schmit trigger
i read the web page you sent me and i have copied the large cicuit.
i am getting a very small pulse. (which is a great sign) if a change the resistors and the cap will that put more current in to base opening up the transistor
Quote from: jasonspinmaster on February 08, 2008, 09:28:04 AM
what do you mean by taken a dvm
dvm
digitalvoltmeter
analogvoltmeter
voltmeter
to read 0,7 volts or wahat you want
i am getting 0.12 volts low state out off 555 timer with the resistor
sorry
i am getting 1.24volts
You really access to an oscilloscope when you play around with electronics.
Elseway you'll never get any design involving pulses up running correctly.
Perhaps you can buy a cheap one at eBay!!!
Quote from: jasonspinmaster on February 08, 2008, 06:46:38 PM
sorry
i am getting 1.24volts
then use 2 diodes , so the transitor can only switch if mor the 2 volts are on IC555 output.
Pese
THAT say:
if you have less than 2 volts on IC output (in front of resistor
the transistor will NOT conduct.
If 2 volts (and mor arrived , the transistor will go to switch on.
Even if you preferre to switch the Transitor an faster way (shorter on / off times)
use the DARLINGTON circuit !
(Exist in one Transitor - If you hane not . Take an
2N2219 2N3053 BC140 BC327 or like this in Front of the
Power -Transistor (2)
Collector (1) conduct to Collector (2)
or better to + Volts (Supply)
The Emitter(1) connect with BASIS from (2).
& Use an discharge resistor from this POINT to ground 470 up to 1000 ohms
Drive now Basis (1) with the IC555 via 1kohm to 3kohm resitor AND 1N4148 Diode.
so it will work.
Pese
MODIFY:
I seen now in 555 Datasheets.
V (sink is about 0,7 volt @ 10 mA (output , but over 2 volts if requested 100mA and more.
(that higher currents you need if only one Power trasistor must amplify the load.!)
In any way you use less the 10mA (from IC) If yiu prffere to use the Darlington Cofiguration.
because the total amplifying factor is than over 1000 !!
++
as attached: