anyone use knife switches for input selection???

[djn]

I am waiting for the gilding to dry to tacky so I can lay down the gold leaf. It is starting to come together. Pix later tonight.

 

[HeyBill]

Gold leaf. Wow. Can't wait to see pictures. You're quite the builder, based on what I saw on your site some time ago. HeyBill

 

[rif]

Volume control thoughts? Maybe link it into the height the Jacob's ladder climbs�� (where did my rmojis go?!)

 

[djn]

No, No. No Jacob's ladder for this one. Just the com panel from a B52 controlling TVCs.

 

[HeyBill]

You need to tell us where you get all that stuff! Please

 

[djn]

When I started thinking about this project, I started looking at ebay for vintage switches.

 

[djn]

Here is the final product. I still have to wire it up, but that should only be a couple hours.

 

[HeyBill]

You must have gone through the imagination line twice djn. How do you like the sound? HeyBill

 

[djn]

Thanks Bill. I've had the pre amp for two years now and it is the best I've ever heard. This whole process was to add the TVC volume control and 4 inputs, and remote control. It sounds great.

 

[djn]

So, this is just the completed chassis but I intent to start wiring it up tonight. I am using the knife switches to send 5v to the input relays. here is the scheme for the relay and my questions is, where does the ground go on the relay? I am building a regulated PS that will put out the needed 5Vs so should I use the ground on that circuit or the ground for the preamp or does it matter?

 

[djn]

Here is the scheme for the ps

 

[Enzo]

Note the protective reverse diode. Pin 2 of your relay gets the V+ supply voltage, then grounding the other end of the coil energizes it. That would be pin 6.

That assumes the diode is included inside the relay. If the diode is something added outside - as is usually the case - then either end of the coil can be either place. Pins 2 and 6 are the coil. One end to V+ the other to ground. To snub switch arcs, we want a reverse wired diode across the coil.

 

[djn]

Thanks Enzo. Yes, the diodes are internal in the relay. The power supply will be close to the transformer volume transformers. Should I be concerned about the picking up hum from the PS?

 

[djn]

Mounted the TVCs but the shaft do not line up perfectly and there is a spot that gets hard to turn so I will get rubber mounts like these but the right size so it won't put undue wear in the selector switch.

 

[tauro0221]

Hi,
Just a suggestion for you next project that you need to use switches. You can use large magnetic reed switches and a magnet to close the contact. Do a search in EBAY using the following description : Reed Glass Magnetic Switches LARGE 36W 50mm NO SPST . The bigger the better. It will look nice.

 

[djn]

Those are cool looking. Thanks Tauro.

 

[djn]

Bought these off the Bay. Old timey panel lights to show which input is active. I think they'll go to the right of the knive switch. I'll load them with LEDs to keep the load down.

 

[djn]

I was surfing the bay a saw this turn of the century power switch and had to have it. I think it is a great addition.

 

[yngvejos]

Awsome build! I like the steampunk style. 🙂

 

[djn]

Thanks Y.