Need someone to build a circuit for me...

[Breaker19]

Hey all.. I am not an EE or even profess to be close to your level, but I have a basic electronics background. The operative term is basic. I need someone to build a circuit for me. I need a digital volume control that is small and runs off 12-14 VDC which will ramp up or down line signal output from a device such as a GPS or iPOD or similar, and controlled by two simple buttons -- one up, one down. I need this for a motorcycle sound system I am building. Unit needs basically 4 RCA's for two channels in and two out. I know, I know.. but it's kind-of a custom thing I am putting together, I know there are min-amps out there with built-in volume circuits. I just don't like them. I have everything else in place, but building such a unit is way above my expertise level. I am willing to pay a reasonable amount for labor and of course, 100% of the parts and shipping cost. You can PM me if interested and I can send you the specifics in regards to the specifications I required. Nothing extreme is needed, just something that will actually work. Thanks, I hope someone out there who's smarter than I can help me out..

Tom in Florida

 

[CocaCola]

I can offer up my services to do this, but the sticker price might shock you for a custom one off design, it's simply a costly venture to make custom one offs... Using an over the counter mass produced item will be A LOT more cost effective, exponentially even and I implore you to at least consider that option... But, if a custom design is in your budget and what you really want you can email me with the specifications and I can work up an estimate, be aware that I can easily see this exceeding $100 in a blink...

coca-cola(at)hushmail(period)me

 

[Breaker19]

I can offer up my services to do this, but the sticker price might shock you for a custom one off design, it's simply a costly venture to make custom one offs... Using an over the counter mass produced item will be A LOT more cost effective, exponentially even and I implore you to at least consider that option... But, if a custom design is in your budget and what you really want you can email me with the specifications and I can work up an estimate, be aware that I can easily see this exceeding $100 in a blink...

coca-cola(at)hushmail(period)me

Thanks for your reply. I agree with you completely, but the reason I posted this is that I cannot find a mass-produced version of what I need.. not even close, actually. I've searched and searched online and cannot find one. Do you know of such a product? If so, please send me the data.. thanks again!

 

[CocaCola]

Off hand no I know of no such item, not something I have ever looked for... Since you want two channels controlled by a single set of volume buttons I doubt you will find a commercial device configured like that... But, that begs the question is the extra cost to have one made worth it vs say using two over the counter ones and simply dealing with it?

All in all after I have all the specs I could work with you in more details on design and sorts to keep the cost as low as possible, I just want to make it clear that it gets costly very quickly...

 

[Breaker19]

Off hand no I know of no such item, not something I have ever looked for... Since you want two channels controlled by a single set of volume buttons I doubt you will find a commercial device configured like that... But, that begs the question is the extra cost to have one made worth it vs say using two over the counter ones and simply dealing with it?

All in all after I have all the specs I could work with you in more details on design and sorts to keep the cost as low as possible, I just want to make it clear that it gets costly very quickly...

I'll draft what I have in mind and send it to you, probably in the morning, I'm heading off to watch the debate shortly... but if you know of a single-channel version, clue me in also, I can't even find one of those! Thanks.

 

[Harald Kapp]

Something like this?

 

[Breaker19]

Something like this?

Yes. I've seen that before while looking for such an item. Unfortunately, the schematic isn't around anywhere. The one I'd need is only different by requiring RCA's on both the input and output. And it's must run off 12 volts. I think this one would, I see that 3-pin power regulator IC sticking up there, that one from Radio Shack (I forgot the number) can be used to build a 12-volt to 5 volt power regulator. I sorta recognize that part. I can't see the number on the chip or what his pin-out is, however... that's where you guru's come in..

Thanks.

 

[CocaCola]

Yes. I've seen that before while looking for such an item. Unfortunately, the schematic isn't around anywhere.

The schematic is straight out of the DS1802 datasheet, and can be found at the bottom of that page it can also be found if you do a Google image search for 'DS1802 schematic'... There seems to be a decent amount of negativity towards that chip on audiophile sites, mostly because it uses a single +5V supply, instead of a dual supply that causes clipping and overhead problems...

The one I'd need is only different by requiring RCA's on both the input and output.

Just a minor tweak...

I see that 3-pin power regulator IC sticking up there, that one from Radio Shack (I forgot the number) can be used to build a 12-volt to 5 volt power regulator.

7805 linear regulator...

 

[Breaker19]

The schematic is straight out of the DS1802 datasheet, and can be found at the bottom of that page it can also be found if you do a Google image search for 'DS1802 schematic'... There seems to be a decent amount of negativity towards that chip on audiophile sites, mostly because it uses a single +5V supply, instead of a dual supply that causes clipping and overhead problems...

Just a minor tweak...

7805 linear regulator...

I'll check that out! Thanks!

 

[Breaker19]

I'll check that out! Thanks!

I looked at a circuit that looks simple enough with this IC but it showed a +15 volt supply. Think it'll work on 12the volts (12-14.3 range)...? It has a 1.5k resistor online does that drop the voltage to the 5 volts mentioned earlier?

 

[CocaCola]

The circuit uses a 7805 5 Volt regulator, it should operate fine from about 7 - 20V input, but a heat sink should be used in excess of 9ish Volts in most cases...

 

[Breaker19]

Hey all, thanks everyone for your help, I did build the circuit with a DS1802 and finished it today, it works great! I bench tested it for quite awhile running to ensure stability, so far so good! I am mounting it in a project box which has four RCA jacks for the input/output. I'm now figuring out the control part, I am not using the mute feature or balance, just volume up/down and I have to find a small momentary switch that'll go up and down, so to speak. And I did heat sink the regulator, it doesn't get warm at all, so that seems to be working. Again, thanks a bunch!

 

[Chat_Ghosty]

Is there anyway you could use a PIC with Transistors to control the Volume?