Hi All
Thats quite a debate! Thanks for your input.
The 555 and analog switch turn the mic on and off at a variable rate. Why?
The circuit has already been heavily modified with a TDA2003 amplifier and sound to light unit attached, it's on here elsewhere from technical queries
I had as i got it sorted with the forums help. Basically the main circuit as seen
is a 'robot voice' changer. With the added amplifier and sound to light unit it is
now being used by around 30 people who have fitted it into their full size Dalek's. Google Dr Who if your not familiar with it. The LM358 due to it's 'rough' function actually 'enhances' the sound wanted a raspy, metallic type
voice on top of the 'chopping' effect but the TL IC you refer to is on my list of suitable replacement parts. The circuit works great for it's intended use but I was just wondering if it was possible to tweak the input of the mike
so that loud external noises (outside the prop itself) aren't picked up to easily
by the mic, also because of the close confines of the prop careful positioning and installation methods for the speakers have to be observed to avoid feedback without having to lower the output volume to the detriment of the 'performance'. A graphic equalizer inline would allow the frequency's that cause any feedback to be controlled but the whole point has been simplicity for the guys (& girls) who decide to build this design. It has been pointed out that a highly directional mic is preferable but if I can offer information of how to 'tweak' the design in the event of having an omni-directional or just plain too sensitive a mic it will be all to the good. I have a really good headset from a call center which I have modified with 2 Jack plugs to use with the design and I can stand 3 feet behind the speaker, which is on the kitchen counter, and have the volume at a very loud level without feedback unlike the
£9.99 headset I had first which could pickup a mouse fart at forty paces in the house over the road and have feedback with the volume appreciably lower than I can have it now. Any hoo I will try the coupling cap from mic to pot as well as the rejig just behind the pot. values for the additional cap would be?
regards
Fenris