Radio kit/Capacitor Help!

[jman116]

I bought a radio kit which is missing a capacitor. The capacitor which is missing has a value of 0.1 uF, can I use different values, like one that I have for 10uF? I am assuming that the capacitor is used for smoothing the signal. Will it work as long as it can supply .1 uF or more? Thanks.

PS It's a kipkay kit, and it was missing more parts, but I can just make the beginner one, instead of the hobbyist one.

[Electronics Wizardy]

Use the same value. If you give the schmetic, i can see if something else would work 

 

[jman116]

1 minute ago, Electronics Wizardy said:

Use the same value. If you give the schmetic, i can see if something else would work 

 

http://kipkaykits.com/fm-radio/

That's the link which has both schematics and both parts lists.

I ORDERED the hobbyist but basically received a beginner kit.

[jman116]

3 minutes ago, Electronics Wizardy said:

Use the same value. If you give the schmetic, i can see if something else would work 

 

[Electronics Wizardy]

2 minutes ago, jman116 said:

http://kipkaykits.com/fm-radio/

That's the link which has both schematics and both parts lists.

I ORDERED the hobbyist but basically received a beginner kit.

Those caps are being used as a high pass filter, and can't just be replaced with a different value, it would work, but it probably pull too much power form the chip and may burn it out. It also gets rid of dc offset.

[LabRat]

sounds like a question for EEVblog.................. I would write/e-mail the company and make them send me one.

[jman116]

26 minutes ago, Electronics Wizardy said:

Those caps are being used as a high pass filter, and can't just be replaced with a different value, it would work, but it probably pull too much power form the chip and may burn it out. It also gets rid of dc offset.

Where did you learn all of this?!?

I want to learn, obviously

[jman116]

20 minutes ago, LabRat said:

sounds like a question for EEVblog.................. I would write/e-mail the company and make them send me one.

Does EEVblog run the kipkaykits?

[jman116]

22 minutes ago, LabRat said:

sounds like a question for EEVblog.................. I would write/e-mail the company and make them send me one.

I'm emailing the KipKayKit's support, they do ship replacement parts, they'll probably (hopefully) send me a new unit free! 

[LabRat]

3 minutes ago, jman116 said:

Does EEVblog run the kipkaykits?

http://www.youtube.com/user/EEVblog

[Unimportant]

You mean the 100n capacitor between VCC pin 5 and GND on the TEA5767? That's just there for power supply decoupling, the circuit should work fine without altough there could be the tiniest extra noise on the output. Replacing it with a bigger capacitor will render it pretty much useless as it will then no longer filter the high frequencies it's meant to, you might as well put no capacitor in in stead of a bigger one.

[jman116]

Just now, Unimportant said:

You mean the 100n capacitor between VCC pin 5 and GND on the TEA5767? That's just there for power supply decoupling, the circuit should work find without altough there could be the tiniest extra noise on the output. Replacing it with a bigger capacitor will render it pretty much useless as it will then no longer filter the high frequencies it's meant to, you might as well put no capacitor in in stead of a bigger one.

Hah, I just read about that too, it called it a bypass capacitor.

Is that the one you're talking about? the .1 uF?

I have a small orange capacitor that says 22 on it, can I use that?

[Unimportant]

No, that would be 22pF, about 5000 times smaller then 100n. It would only filter frequencies so high they're not a problem anyway.

[LabRat]

doesn't the frequency change?

look at the voltage on it too.

[jman116]

Just now, Unimportant said:

No, that would be 22pF, about 50 times smaller then 100n. It would only filter frequencies so high they're not a problem anyway.

I'm also missing 2 different resistor values that're used for contrast and backlight control.

Could I use 2 potentiometers in that case? They're both from an old turtle beach headphone set.

I'll also just leave out the capacitor, it seems like it's not needed.

[Unimportant]

The 67 Ohm backlight resistor should not be replaced with a potentiometer, a pot will range from 0 to x ohms where x is the value of the pot. Turning the pot the wrong way (0) will blow the LED in the backlight. If you want adjustable backlight you can use a pot in series with a fixed 67 ohm resistor so you can never go below 67 ohm.

 

Constrast could be done with a potentiometer as long as the value is not off by orders of magnitude.

[jman116]

1 minute ago, Unimportant said:

The 67 Ohm backlight resistor should not be replaced with a potentiometer, a pot will range from 0 to x ohms where x is the value of the pot. Turning the pot the wrong way (0) will blow the LED in the backlight. If you want adjustable backlight you can use a pot in series with a fixed 67 ohm resistor so you can never go below 67 ohm.

 

Constrast could be done with a potentiometer as long as the value is not off by orders of magnitude.

So if I replaced the 67ohm resistor with a higher value it'd work but be darker?

I have afew lying around which are near that value

[Unimportant]

Just now, jman116 said:

So if I replaced the 67ohm resistor with a higher value it'd work but be darker?

Yes, it will get darker the higher the resistor value goes up until the point the LED's no longer reach their forward voltage, then it will cut out.

[jman116]

5 minutes ago, Unimportant said:

The 67 Ohm backlight resistor should not be replaced with a potentiometer, a pot will range from 0 to x ohms where x is the value of the pot. Turning the pot the wrong way (0) will blow the LED in the backlight. If you want adjustable backlight you can use a pot in series with a fixed 67 ohm resistor so you can never go below 67 ohm.

 

Constrast could be done with a potentiometer as long as the value is not off by orders of magnitude.

I have 2 100 Ohms 1% resistors, (Brown, black black black Brown) and another whose value is either 10k (Brown Black Black Red Brown) or 120 Ohms (Brown Red Black Black Brown)

Edited July 23, 2016 by jman116
Colors

[Unimportant]

You could try 100 ohm for the backlight. Might be a little dim but would probably work.

[jman116]

Just now, Unimportant said:

You could try 100 ohm for the backlight. Might be a little dim but would probably work.

Would that work for the contrast as well or would it be really dark/light?

I can't tell what this other resistor's value is, there's no indication of which side to read from!

[Unimportant]

2 minutes ago, jman116 said:

Would that work for the contrast as well or would it be really dark/light?

Normally, contrast on these LCD's is set with a potentiometer (10K for example) between VCC and GND and the center tap to the LCD contrast pin. Then you adjust the pot until you get a image. When connecting things straight to VCC trough a fixed resistor like done on the scematic it'll have to be the correct value.

[jman116]

1 minute ago, Unimportant said:

Normally, contrast on these LCD's is set with a potentiometer (10K for example) between VCC and GND and the center tap to the LCD contrast pin. Then you adjust the pot until you get a image. When connecting things straight to VCC trough a fixed resistor like done on the scematic it'll have to be the correct value.

So I can use the pot for the contrast, just not the back light?

[Unimportant]

3 minutes ago, jman116 said:

So I can use the pot for the contrast, just not the back light?

For contrast yes, as long as the pot's value is reasonable, anything from 1K to 100K should work. Connected like this:

 

Use the 100 ohm for the backlight.

[jman116]

Just now, Unimportant said:

For contrast yes, as long as the pot's value is reasonable, anything from 1K to 100K should work. Connected like this:

 

Use the 100 ohm for the backlight.

Thanks, I'll try that!