don't understand circuit operation. please help!

do i need to use the isolation transformer? because i already have a step down transformer. what's the function of the isolation transformer?
I'm attaching the circuits that i draw with orcad. can you look it over and see if it's okay?
thanks
fiz

The isolation tranformer need only for developing, because the scope signal input GND connected to mains GND (earth - third pole on socket).

60W bulb

hi,
i got some problem with the power supply. the output from voltage regulator is 0 not 5V. i tried using a 9VDC for the input and got 5V at the output. but the battery got hot and when i tested it later the voltage at the output is 0V. i also tried connecting 240V directly to the 4005 diode but still no use. how to fix this?
another thing for the receiver circuit, i replace the 2n400 with bc337 transistor. my friend told me to drive a 60W bulb i need to use a relay and 240V. Is it true? how can i do this?
thanks
fiza

tuned amplifier

the transmitter circuit got a section on tuned amplifier and untuned amplifier connected to the 4069 inverter. can anyone tell me how the tuned and untuned amplifier works?
when i connected/solder the tuned amplifier circuit, all four capacitors and the axial inductor are in parallel position. so when i test the leads for the capacitors using digital multimeter it beeps. is it okay?
thanks
fiza

Hi!
I am doing the X-10 tranciever circuit. I have a problem finding the 7,680MHz X-tal. My question then is; is there a way I can use a single crysta (a 4MHz possible) instead of two x-tals, and how do I interface it?

7,680,000 was chosen as it divides evenly into 120kHz (the X10 carrier).

Hi

I tried interfacing my circuit with a 4MHz crystal Instead of the 7.680MHz and 32kHz respectively but my circuit didn't work. I still would like suggestions on how (if possible) I can interface the 4MHz X-Tal. Also, are the 2 LTL-94PEKTA (D1 & D2) LED's ordinary general purpose LED's? If not, what are they.

Almost forgot; I'm designing the circuit for 250V/50Hz supply. What components values do I need to change for this voltage?