The transistors do not necessarily have to be bc547 you may use 2n2222 or similar small signal transistors but it is recommended to always use the equivalent transistors.
Transistor flasher circuit diagram.
This circuit basically works on the charging and discharging of capacitors.
In the first circuit a flasher circuit in series with a 220 ohm resistor turns on a power transistor.
The two circuits below are typical connections.
Here is a one transistor led flasher circuit which will flash a super bright led.
And instead of led how can i connect transistor which can act as a switch the transistor switch will be on for 1sec and off for 1sec 2 the circuit diagram is shown in the link below.
I have many ways but today you see this three of the lamp flasher circuits.
Power transistors may be added for handling higher current loads.
The circuit is using 2n3904.
The circuit is using single transistor as driver which is taking flash rate from the led 2 which is a self flashing led.
Can be used on roads for signaling purposes.
Both npn transistor you can use of bc547 548 or 2n2222.
This circuit can be operated using dc 6 12v supply.
The flash rate can be adjusted by changing the value of 1k resistor used in the circuit.
It can work as well as the use of ic 555 or other transistor circuits.
If you want one a lamp flasher circuit using transistors that flashing for general to use.
In the second circuit a power fet is used in place of the npn.
Circuit diagram blinking led circuit.
This led flasher circuit is very easy and simple and there is no ic used.
Use 9v or 12v battery or adaptor for this circuit.