I've tried a number of times with my HP Laserjet 4050TN printer, but it's too frugal with the toner. I can't seem to get it to print dark enough.

 

hi there

thats a bit of a pain then. no controls for quality or density in the printer software? That said for 2 A4 sheets with 4 patterns apiece it cost me only UK 18p so you may be better going to a high street printers and just ask them to set the density of the print to high.

Regards

Fenris

 

Hi Bertus,
You need a lot more base current than the hFE calculation to saturate a switching transistor. Darlingtons need a base currennt that is 1/250th of the collector current to saturate even if their hFE at a higher VCE is 1000.

You had the output transistors always turned on.
My circuit has the output transistors turned off when they are supposed to be off but there is not enough base current from the transistor that drives the BD139 for a 4A output. My circuit has a 1mA base current for the BD139 but 16mA is needed.

 

Hello audioguru,

You are correct darlingtons are a powerfull kind of transistors.
I have hardly used them.
Is it possible to drive the 4A lightbulb with you settings?
How much AC from the audio is needed to let the lightbulb shine bright?

I know class C amplifiers (from the RF experience), where no bias current at all is given.
You must give a sertain input to see something on the output.
This is off course non-lineair.

I think that afther 30 years in electronics, I can still learn something.

Greetings,
Bertus

 

I would like to thank you all for your assistance. I now have a voice mod with a functional sound to light system built in. Heres a picture of the circuit in it's box and a link to a video of it working. The 'voice artist' is my mother in law .

http://s200.photobucket.com/albums/aa97/Fenris_2007/?action=view&current=SV600050.flv

Regards

Fenris

 

The sound has a squeak at about 3kHz. The sound is chopped at about 10Hz.

Is that what you want?

 

The chop rate is variable. The squeak however is not desired. I am going to put the unit in one room close the door and talk into the mic to see if its just feed back. I have posted a query as regards the TDA2003 amplifier circuit to see if im tweaking it correctly. Got to try the room and door test first though as advised there.

Regards

Fenris

 

Hi all

Good news!!!! I have solved the chirping. It seems it was the sound to light portion of the circuit. A confab with another electronics type person and a good nights sleep i have fixed it. The negative supply for the amplifier circuit was more or less at the end of the run right in the middle of the 7555/4066 modulation circuit. I have removed a piece of track to isolate the amp from there and instead i have fitted a wire link (8mm long) to take the negative supply directly to the amp from the terminal point of the PCB. The only other change is to 2 wire links that went from the amplifier to the input of the sound to light they have been removed and changed to a twisted pair which now arch from one side to the other so they are well clear of the -ve and +ve tracks that run between them. one or other of the changes did it but whether it was poor supply layout or interference crossing the power and audio lines but it works a treat now.

regards

Fenris

 

Hi all

heres a link to a brief vid of the now perfectly working unit. I have 3 now!!!

http://s200.photobucket.com/albums/aa97/Fenris_2007/?action=view&current=SV600059copy.flv

regards

Fenris

 

You say it works perfectly?
It sounds horrible.

 

It's meant to sound horrible. Haven't you watched Dr. Who?

 

Yes its meant to sound horrible as Bill says. It is after all the voice for a pretty horrible alien. . Its going down a storm on the dalek forum.

regards

Fenris

 

It's meant to sound horrible. Haven't you watched Dr. Who?

Who is Dr. Who?
Wikipedia says it is a British TV show. I haven't been to Britain for about 43 years. I don't think the British TV show is played here in Canada.

 

Hi Audio Guru.

You have been robbed!!!!!!!!!!!!
Basically the Dr is the main character of a long running Sci-Fi series on BBC1 in the UK. Its been running since 1963 apart from an break of 15 years because of some short sighted numpty in the BBC. He is a time lord and travels in a time machine that looks like a Police box (another British thing). Which is called the TARDIS. It travels through time and space. The Daleks are one of the iconic enemies of the Dr and are hugely popular over here and else where where the series has been aired. It is a great show if its your bag and of course with developments in CGI and technology the new series has benefited hugely. Every one who builds a full size replica of the many variants of the Dalek machine craves a voice mod to do the 'voice'. pop over and look at www.projectdalek.com for a bit of info on the Dalek 'cult'.

Regards

Fenris

 

Fenris,
That's great! I'm laughing out loud at the results - it really is a very good likeness!!

Now you just need to build a few Daleks big enough to drive around in.

AudioGuru, I'm surprised you don't get Dr. Who on one of the stations up there.

It was on the SciFi channel last night here.

 

My dad was stationed in Britain when the show premired, and I caught it. Ruined me for life it did.

 

But what a way to get ruined . Wine, women, and Dr who!

regards

Fenris