On-delay circuit not working

Question

I'm trying to make On-delay circuit with passive components, I use 3 identical AAA alkaline batteries (4.5 v) and use PNP 2N2907 Bjt with 600mA Collector Current to heat(glow) up a small resistor wire

I use a 1000 uF capacitor and 20k Pot resistor for adjustable RC delay, Also I use 6.1v Zener diode however, when I press push button in my circuit the heating element does not even warm-up

following is my schematic

my question is:

Is Bjt not powerful enough to deliver current and heat up the element,

or is my schematic wrong and I should select another component?

if the current is not enough how can I add a wire coil inductor to charge on delay and push more current to the heating element?

updated schematic

updated schematic base on new comments

Answer 1

You are trying to turn on a PNP transistor with a positive voltage from base to collector, to turn on a PNP you need a negative voltage from base to emitter.

Another problem is that you are using a 6.1 V Zener but your batteries only supply 4.5 V, so the Zener will never see enough voltage to conduct. You would either need higher voltage from the batteries or a different circuit altogether.

You could try an NPN transistor and swap the emitter and collector around, but you need one that will handle the cold current of the wire and enough base current to saturate the transistor which may require using another transistor as a driver.

Other options are a MOSFET or a relay, although a relay would add extra drain on the batteries.

You need to take the initial inrush current into account. A heating wire will have a low resistance when cold and then the resistance will increase as it heats up. This will cause a large current draw on startup than when in operation. You can deal with the inrush several ways, either use a device that can handle the maximum inrush current, or limit the inrush current.

Answer 2

That time delay circuit needs a complete redesign, so here is my idea for something that should work. It uses an NPN/PNP pair as an SCR, so it will latch on and remain on as long as power is applied.