Spectratone

[Sonny ReVerb]

I've been playing around with a Wurlitzer Spectratone I pulled from an organ. I'm trying to make up a power supply and control circuit for it.

[img:240:238]http://farm1.static.flickr.com/193/5102 ... d62f_m.jpg[/img]

The motors run on 120VAC. It uses a 24V relay to switch speeds. There is also a 6V(?) incandescent bulb that works with two LDRs and an eccentric wheel that the organ used for additional tone shaping.

I have a 25.2VAC transformer for power. I want to power the relay, add a power on LED, and an LED that mimics the rotational speed via the lamp/LDR.

(To demonstrate my lack of electronics knowledge... ) Here is what I tried but had no luck with:

[img710]http://img693.imageshack.us/img693/9072/spectratone.jpg[/img]

I'm only getting ~19VDC after the FWR. I was thinking a FWR should produce (25.2-0.7) x 1.4 = 34VDC, but I guess Vpeak is only 12.6 so I'm only getting about half of that. Does that sound right? I think the current draw of the lamp, etc. is swamping the voltage divider, as well.

So, how can I get this up and running? Maybe a voltage doubler to get enough DC for the relay? Should I run the lamp from the main DC supply rather than the voltage divider because of the current draw? Then I could run just the LEDs from the voltage divider.

I know, this will never sound like a Leslie, but it was free. Should be fun for bedroom levels or maybe recording.

[Jana]

You are using a full wave rectifier, not a full wave bridge which is the 1.414 multiplier (also 2 diode drops).

[Sonny ReVerb]

Thanks, Jana. You're right, I need to try the FWB. I thought full wave was full wave, but I finally found a good reference that explains the difference between the conventional full wave with CT versus the FWB.

One advantage of a bridge rectifier over a conventional full-wave rectifier is that with a given transformer the bridge rectifier produces a voltage output that is nearly twice that of the conventional full-wave circuit.

I did some further testing on the lamp in this thing. I'm pretty sure it's a 12V lamp, not 6V. At 12V it's pulling around 200mA, which I found is a common current rating. At 6V it's only pulling 140mA.

That's, by far, the biggest load in this circuit. The relay only needs 35mA when energized and the LEDs are around 20mA each. The transformer's rated at 450mA, so if I can get the voltage out of it, it should be fine.

I'm considering using a 12V zener instead of the resistive voltage divider.

[Sonny ReVerb]

Got the power supply worked out on this Spectratone project. I used an interesting 'Economy' PS circuit I found on the web.

[img:800:582]http://img189.imageshack.us/img189/9072/spectratone.jpg[/img]

[img:800:450]http://img341.imageshack.us/img341/7815 ... rdcomp.jpg[/img]

[img:800:600]http://img231.imageshack.us/img231/8140 ... copper.jpg[/img]

Started on a cab for it as well.

[img:577:800]http://img715.imageshack.us/img715/8087 ... abrawf.jpg[/img]

[img:600:796]http://img718.imageshack.us/img718/2448 ... abrawb.jpg[/img]

[Structo]

I assume you are going to use this with a guitar amp?

What does it do?

Is it similar to a rotating speaker Leslie type thing?

What app did you use for drawing the schematic?
Looks nice!

Nice work on the cab!
I want to learn how to do box joints like that for a head cab.

[Sonny ReVerb]

I assume you are going to use this with a guitar amp?

What does it do?

Is it similar to a rotating speaker Leslie type thing?

It's a Wurlitzer version of a Leslie. Yes, I'm going to use my guitar amp to power the speakers. It only has two 4" speakers back-to-back. I'm not sure how it will sound with guitar, but it's fun to mess with. The speakers measured 1.9 ohms so I figured maybe a 4 ohm load. I'd like to use it in parallel with my 8 ohm cab. If that stresses the OT I'll have to figure out some other setup.

What app did you use for drawing the schematic?
Looks nice!

This was my first attempt with PCB Wizard. I like how it turned out. The only problem is there aren't many larger/HV/axial parts in the components library. You can create your own components, but I haven't mastered that yet.

Nice work on the cab!
I want to learn how to do box joints like that for a head cab.

Thanks, Tom. The box joints are nice and strong. They take a lot of setup time to get right. After the jig is dialed in, they're pretty easy to knock out. This cab was a bit tricky because the top and bottom are 3/4" pine and the sides are 1/2" BB ply.

I've already got Tolex on it, but I haven't taken any pics yet.

[Baxtercat]

I bet this thing is going to sound so cool!
The rotor mechanism reminds me of the thing they used to spin poor astronauts in.
[IMG:350:240]http://i914.photobucket.com/albums/ac34 ... xt/p16.jpg[/img]

[M Fowler]

Interesting project and everything is looking good.

If I ever get a Hammond XK1 or XK2 a leslie cab will be needed for sure.

[Sonny ReVerb]

Nearing completion on the Spectratone. This thing turned out pretty nice. Only problem is, the speakers sound a bit suckish (as my daughter would say). I'm not sure if the speakers are working properly, but they have pretty low output and distort easily. The vibrato effect is wonderful, but this thing would never cut it beyond low level recording.

I'm sure the stock speakers are fairly inefficient. I haven't seen many 4" guitar or MI speakers. The closest I've come up with is some car speakers. Anyone have any suggestions?

Here are some pics:

[img:600:800]http://img291.imageshack.us/img291/1112 ... tolexf.jpg[/img]

[img:800:600]http://img175.imageshack.us/img175/7978 ... plate1.jpg[/img]

[img:600:800]http://img190.imageshack.us/img190/4244 ... plate2.jpg[/img]

[img:800:600]http://img808.imageshack.us/img808/3562 ... eguts2.jpg[/img]

[img:800:600]http://img231.imageshack.us/img231/8837 ... neguts.jpg[/img]

[img:800:600]http://img375.imageshack.us/img375/4753 ... eptbrd.jpg[/img]

[img:600:800]http://img337.imageshack.us/img337/6973 ... tsback.jpg[/img]

[img:600:800]http://img685.imageshack.us/img685/373/ ... tolexb.jpg[/img]

[M Fowler]

Parts Express speaker selection.

[torea]

Hey all, first post here. I figured I'd revive an older thread before starting a new one.

I picked up a Wurlitzer Tone Cab with a Spectratone in it. The looks great, but the amp appears to have been scavenged by Jawas.

Anyway, I'm looking to build an amp or hook this thing up to an amp. It has 2 12" speakers, 2 3" speakers, and 2 4" rotating speakers. The speakers and wires are all intact, but have nothing to connect to. The motor that spins the 4"s is intact but stuck. It's loosening up slowly.

I'm guessing I need a crossover to send bass to the big and highs to the small/rotating speakers. Then a separate control for the speed? The motor has an AC plug in it, but that looks like it was added to an existing cable.

Any points in the right direction are greatly appreciated. I'm no expert at all in amp building, but would like to use this as an opportunity to learn =D


Thanks!