circuit fade

[ronv]

Almost there!

1- If you have addwd any resistors in series with the input signal remove them. I put one in the drawing to represent the protection that may be in the computer.

2- Change the input capacitor to 10 Ufd. This is needed because the input frequency is kind of low.

3- Change C2 to 10Ufd. and move it to the collector of the transistor to ground.

 

[camerart]

Almost there!

1- If you have addwd any resistors in series with the input signal remove them. I put one in the drawing to represent the protection that may be in the computer.

2- Change the input capacitor to 10 Ufd. This is needed because the input frequency is kind of low.

3- Change C2 to 10Ufd. and move it to the collector of the transistor to ground.

Ronv, I have changed the circuit, is this what you suggest? (see attachment)

MR RB, I am trying with only 1 channel, so no connecting resistors.
Also you suggested a capacitor across the opto LED. Was this to smooth the tone frequency? You said the LED will stay on, but I would have thought it should switch on and off, can you explain please?

 

[ronv]

Yep, That's it. Lets see if it works.

 

[Mr RB]

... MR RB, I am trying with only 1 channel, so no connecting resistors.
...

That's fine, there is no need to use two stereo channels now as you are not trying to get enough power to run a LED direct from the sound card. Just running from the left or right stereo channel is simpler and safer, but MAKE SURE to still use a stereo jack plug so you don;t short out the unused channel!!

...
Also you suggested a capacitor across the opto LED. Was this to smooth the tone frequency? You said the LED will stay on, but I would have thought it should switch on and off, can you explain please?

Yeah that was a minimal parts kludge to try to reduce the flickering of the LED but would not really have removed all the flickering. Ronv's suggestion of moving the cap to the transistor collector is better to reduce LED ripple for sure, although you might need a bigger cap. You can 'scope for the collector voltage when running, and if the voltage ripple is more than a volt or so the cap should be increased.

Putting the cap across the collector like that can be unsafe in some situations as it acts as a short circuit to the transistor when it first turns on, however it is probably safe in your circuit as the trasistor is turned on gently by a low current sine wave, both things the reduce the turn on collector current. If you want a bit more safety then a 100 ohm resistor directly in series on the collector wire will reduce peak currents and also give a benefit of further reducing the LED current ripple. Note if adding that resistor you might need to increase the cap to 47 or 100uF.

 

[camerart]

SUCCESS!!!

I'll need to make a new circuit to replace the Christmas tree, and will add those extra suggestions. Then I'll have to try it in transmission mode.

Thanks to al concernled. MERRY CHRISTMAS.

Camerart

 

[ronv]

Ho, Ho, Ho. Glad it works.

 

[Mr RB]

.- -. -.. .- .... .- .--. .--. -.-- -. . .-- -.-- . .- .-.

 

[camerart]

.- -. -.. .- .... .- .--. .--. -.-- -. . .-- -.-- . .- .-.

.- -. -.. .- .... .- .--. .--. -.-- -. . .-- -.-- . .- .-. - ... -.-- --- ..-

I have had my licence for 27 years. Up to now I have only listened. Thanks to all on this thread and others, I transmitted and received messages for the first time yesterday.

Cheers, Camerart. And for those who don't read morse, HAPPY NEW YEAR.

 

[camerart]

Just for interest, if anyone is still subscribed.

After all this time, I have just received an answer to an email to Toshiba, asking what voltage do the earphone sockets supply. In short, 50mW/Ch @32 Ohms. The output is variable depending on impedance.

Regards, Camerart.

 

[ronv]

Something good to know.

 

[camerart]

Hi Ronv,

Yes, it illustrates why I was getting some of the strange results

 

[Mr RB]

That's about 1.26v RMS when driving 32 ohms, and should be >1.5v or so into a light (high impedance) load. It sounds about typical for a headphone socket but I think your output was far below that!

I'm curious if you connected a 32 ohm resistor as a load and turned up all the volume controls in Windows, what output level you are actually getting there...

 

[camerart]

That's about 1.26v RMS when driving 32 ohms, and should be >1.5v or so into a light (high impedance) load. It sounds about typical for a headphone socket but I think your output was far below that!

I'm curious if you connected a 32 ohm resistor as a load and turned up all the volume controls in Windows, what output level you are actually getting there...

Hi Mr RB,

You appear to have misread what I said in #69. I was referring to an answer from Toshiba, to a question I asked a month or so ago. The voltage varies according to impedance. I have never quite understood resistance and impedance, but the output voltage depends on it.

Cheers, Camerart.

 

[Mr RB]

Yeah I saw that was a spec from Toshiba. What I was saying is that your laptop's measured results so far have been far away from that spec.

 

[4pyros]

Its posible something got damaged when trying to use the mono plug.

 

[camerart]

Yeah I saw that was a spec from Toshiba. What I was saying is that your laptop's measured results so far have been far away from that spec.

I think this was because I never had it properly set-up with 32 ohm impedance (Don't quite understand!), while was measuring.

 

[camerart]

Its posible something got damaged when trying to use the mono plug.

I think the circuit protection, did it's job and protected the circuit from my meddling, it's working fine, and sending morse ok on one channel.

 

[nahid_tct]

I have a IP phone. But it's haven't any battery. So when electricity gone then phone is fully stop. At this moment I need a battery backup for my ip phone. It's have 5v 1a adapter.

Now please help me how can I insert a battery in my IP phone?

 

[picbits]

I have a IP phone. But it's haven't any battery. So when electricity gone then phone is fully stop. At this moment I need a battery backup for my ip phone. It's have 5v 1a adapter.

Now please help me how can I insert a battery in my IP phone?

Its rather rude hijacking someone elses thread to ask your own question, especially as you already have a thread open with the same question here ?
https://www.electro-tech-online.com/threads/need-ip-phone-battery-backup.132313/