ParkingLotLust
Member
My original thread is here.
I found this circuit on the interwebs:
**broken link removed**
According to the description:
This seems like exactly what I want. However, I have a couple questions:
- how would I modify the circuit to accept speaker-level inputs and outputs, vs line-level (RCA) in/out?
- I only have TL072 and TL074 chips - could I use one of them in place of the TL082?
- I wont be able to get the LDR/LED chip in the time space Id like to have it done by, so can I use a LED and LDR coupled together with some heat shrink?
- If so, what colour LED should I use?
According to the datasheet of the LDR/LED chip they used, the LED has a forward voltage of 2.0v so this makes me think its a red LED. Also, the LDR has an on resistance of 40 ohms @ 20mA and 140 ohms @ 1mA, and an off resistance of 1-5 Mohms. Is this typical for an LDR?
To make it easier on whoever helps me, here are the datasheets I am referencing:
TL07x
TL082
LDR/LED Chip
Original schematic page
I found this circuit on the interwebs:
**broken link removed**
According to the description:
There's one by Terk (Audiovox) for about $25 on line and $40 in stores. It's gotten mixed reviews. Besides, I need three, so I built this one and it works fine. Now we have constant volume on all the channels.
How does it work? It's inserted between the TV and the DTV or HD box or DVD box using standard RCA audio cables. It takes the signal from the box and amplifies it to a point where it doesn't amplify any further, resulting in constant volume.
It uses a light dependent resistor (LDR) that shunts the input to ground as the input volume increases. The circuit is based on one in EG&G Vactec's application notes. I couldn't get their circuit working right, so I made some changes and added an input amp and output buffer to get the levels right.
This seems like exactly what I want. However, I have a couple questions:
- how would I modify the circuit to accept speaker-level inputs and outputs, vs line-level (RCA) in/out?
- I only have TL072 and TL074 chips - could I use one of them in place of the TL082?
- I wont be able to get the LDR/LED chip in the time space Id like to have it done by, so can I use a LED and LDR coupled together with some heat shrink?
- If so, what colour LED should I use?
According to the datasheet of the LDR/LED chip they used, the LED has a forward voltage of 2.0v so this makes me think its a red LED. Also, the LDR has an on resistance of 40 ohms @ 20mA and 140 ohms @ 1mA, and an off resistance of 1-5 Mohms. Is this typical for an LDR?
To make it easier on whoever helps me, here are the datasheets I am referencing:
TL07x
TL082
LDR/LED Chip
Original schematic page