The circuit simply goes like this:
The base of the transistor is a logic signal which came from an external circuit supplied by the same 6V source as that of the collector. The logic signal can either be 0 volts or 6 volts. The external circuit consists of a PIC and an op amp.
The 6V supply come from a 6V lead acid battery. Also, I used different voltage supply on the transistor and the dc motor, so I used two 6 Volts battery in all (including the external circuit), separately.
Without the 3 Volts dc motor, the relay switched properly when the input is logic 1 (6V), and closed properly when logic 0 (gnd). So, no problem with the relay.
The problem is: With the dc motor attached on the switch contact of the relay, and a logic-1 is applied on the input, the switch on the relay repeatedly opens and close (that is, the dc motor rotates and stops repeatedly).
I tried forcing the value of the input to 6V without the external circuit that produces it. The dc motor rotates perfectly fine in that case.
My first thought was that the battery is drained or absorbed (that is, the supply lowered down to 3 Volts when measured) because of the external circuit that produces the input to the base of the transistor. If I am correct with my assumption, how would I eliminate the absorption of the battery?
I tried replacing fully charged 6V lead acid battery but the problem remains the same. How would I solve this?
If you need more info, you may comment below. Sorry I may use wrong terms because I am not an expert on this field.