I measure a voltage of only 0.5 Volts on pin 3 of the 555 Timer on the serial transmitter.

Seeing as it connects to a 220 ohm resistor then to the IR LED that means it only gives the IR like 2-3 mA.

So my transmitter fails to send anything.

I can see it working with an IR video camera but its much much weaker than any TV remote?

Hello,


> I measure a voltage of only 0.5 Volts on pin 3 of the 555 Timer on the serial transmitter.

You can NOT use a Multimeter to measure that.
It is MODULATED with 36kHz and also a pulsed signal.
You would have to use an Oscilloscope.


You need to describe in more detail how you connected it to the PC (USB Serial / Notebook - this often gives to low supply voltage) and what else you tried.
Did you adjust the trimmer properly and did the Terminal Receive test?


> I can see it working with an IR video camera but its much much weaker than any TV remote?

It is lower, yes that is normal but should be no problem. TV Remotes use quite high current usually which is not available on the RS232 Port.

Regards,
SlyD

The 555 chip i think has just died!

The voltage to the IC was about 5-6volts but dropped to 3v occasionally

I tried connecting to the motherboard serial port and also to a USB to serial adapter.

The reflect test never worked in HTerm but i could recieve random bits from tv remotes.

, I think i could have a short but that wouldnt have killed the 555?

Woo

My set came with a faulty 555

I replaced it with a NE555N from ebay and its working well on the reflect test from about 40 cms