Source parts for R.G. Keenes Spyder power supply

[mike_mccue]

In a recent thread I learned about the guitar pedal power supply design by R.G. Keene at geofex

http://www.geofex.com/Article_Folders/Spyder/spyder.htm

I'd like to source the parts recommended but am having some difficulty.

The designs specs a transformer:
Mouser part# 41PG006

a voltage regulator: 78L09

and a rectifier: DB01


The link to the voltage regulator has lots of choices... I'm going to go look and see if it's just various attachment designs.

I can not find much info about the rectifier... is DB01 a form factor? The only references to DB01 rectifiers I've found seem to be for voltages I would not expect with the Spyder design.

Can someone help me narrow down the parts needed?

thanks,
mike

[R.G.]

Hi, Mike.

Since I wrote that, Ted Weber has come up with a custom-made transformer that does what you need, and it's here: and the picture is here.

It has eight 11V windings plus a 9Vac winding, and costs $20. You'll spend $12 on just the transformer to cut apart if you insist on winding it yourself, so I recommend you sidestep the safety and time/money issues and buy Ted's.

Mouser changes their part numbers over the years. This one works correctly : Mouser #
512-DF01M, http://www.mouser.com/Search/Product...252bjpDQ%3d%3d

[mike_mccue]

Hi R.G.,

Thanks for the details about the Weber transformer... I happened to follow up on your article's mention of that part and was looking at it last night at the Weber website.

I'm wondering if there is a choice of bridge rectifier that might be easier to use with a DIY assembly? Maybe I'm unaware of an obvious way to use the rectifier you suggested? It seems best suited to a nice PCB design.

thanks very much,
mike

[R.G.]

Originally Posted by mike_mccue

I'm wondering if there is a choice of bridge rectifier that might be easier to use with a DIY assembly? Maybe I'm unaware of an obvious way to use the rectifier you suggested? It seems best suited to a nice PCB design.

It is intended for PCB work, but it's fine on stripboard or perfboard as well. The only thing it doesn't do well is point to point with no underlying board to mount it on. I do about 90% PCBs these days and perfboard for the rest, but then I've been making PCBs for a long time.

Any bridge rectifier assembly with a rating equal to or greater than 100V and 1A will work, given that you connect the AC and +/- leads to the right places. Maybe the best thing is to look at the pictures in the Mouser catalog.

Go to page 452 in the Mouser Catalog and look at the packaging styles shown. The small bridge I recommended is style G. If you want long leads, any of the styles from I through S will work. They get progressively larger from I to S. You probably want something like a I, J, or K. M lets you mount it to the chassis/board with a screw.

Once you pick the package you like, go look at the listings for individual devices and pick one with a rating of 100V or more and 1A or more. On that page, all of them are 1A or more, and all but a few are 100V or more, so get one you like the package of and at the lowest price.

[mike_mccue]

Thanks very much for the detailed info.

best regards,
mike

[mike_mccue]

I'm beginning the process of sketching out a pcb. Is there anyway to determine the exact size of the Fairchild DF01M you suggested?

For Example the "G" DB01 format by Rectron on page 452 has exact dimensions.

I'm wondering if the DF01M is described in detail somewhere? Maybe Dip4 implies and exact dimension that I can look up in a standards directory?

I'm playing around with expressPCB so it would be nice to have exact dimensions.

thanks,
mike

[Steve Conner]

Sure, go to Fairchild's web site, or ST or whoever else, and download the datasheet for it. The dimensions are always in the datasheet so the PCB guys can check them.

It's just an 8-pin DIP with the four centre pins missing. It might be easier to just place an 8-pin DIP in PCB Express and leave those four pins unconnected.

[mike_mccue]

Thanks Steve,
I got a ST Micro and a Texas Instruments Data Sheet for the 7809 voltage regulators. they have all the dimensions.

The Fairchild data sheet did not have dimensions for the DF01M they just described it as DIP4. The illustration of the DB01 Mr Keene refered me too did have dimensions but they are noticably different from the default 4 pin in the PCBExpress premade symbols. I got that sheet via mouser. I'll go to the Fairchild site and look for more info.

Thanks,
mike

[R.G.]

Most of the DIP-style full wave bridges are in what would be a six-pin DIP package, but with the middle two pins missing on each side. That is, the pins on each side are 0.2" apart.

[mike_mccue]

Thanks R.G.

I've been having fun with ExpressPCB... I'm not sure if I'll pursue getting their service to make a board... but it's been great to learn. I've made etched boards before but I never enjoyed that.

I'm also wondering about the capacitors. My most recent experience is in small guitar amps and I would use electrolytic caps in a power supply filter application but with this design and the voltage regulator I'm wondering if the caps serve the same purpose?

Last night I used some axial 50vDC electrolytic caps for the sketch up in PCB Express. I put the + on the positive rail.

I also have an extra question. Is there an easy way to add small circuit breakers to each output?

Thanks very much,
mike

[defaced]

Yes, the electrolytic serve the same purpose in this regulated power supply as they do in a tube amp's unregulated power supple: filter the rectified AC voltage.

Think of the regulator as another modifier to the power supply. The transformer turns line level voltage into the voltage needed for the circuit. The rectifiers turn that AC voltage into unfiltered DC voltage. The caps filter the rectified DC voltage. The regulator takes the filtered DC voltage and keeps the voltage output constant over a range of current levels.

[mike_mccue]

Thanks,
I used the 50volt Electrolytic size because the lower voltage items just seem so small to work with. Any thoughts?

How about circuit protection? I've looked and see that a "breaker" is probably not an option for such low volt and amps. I can figure out a fuse but do other options exist? Varistors or anything like that?

thanks,
mike

[tigert10]

You might check out General Guitar Gadgets...he has pre-printed ready to solder PCB's for a couple of Power Supply projects. The 4 output isolated seems to use a very similar regulater/filter stage as the Spyder and might be useful. Just a thought.

[tigert10]

I am wanting to build a Spyder using the Weber transformer that RG described. The transformer eight 11 volt, 300ma windings and one 9 volt, 2 amp winding. Do you use the same regulator/filter section (as seen in the Spyder schematic: http://www.geofex.com/Article_Folders/Spyder/spyder.htm) for the 9v 2A winding as you do for the other windings?

[jameskpolk]

Tigert10 - I think that the 9V 2amp winding is meant to power a pedal requiring 9v AC power, so a regulator isn't needed. But I'm a bit of an electronics noob.

Speaking of which, I'm also looking to build the Spyder, and couldn't help but notice that the regulator/filter schem. has no grounds, where similar schematics I've looked at do. This is all part of the "breaking the ground loops" plan, right?

Even so, I feel like I'm missing something...is there any sort of ground, anywhere? If I wire it up, as shown, will I electrocute myself?

[Enzo]

Not ground loops, no.

SOme pedals ground the +9v while others ground the -9v. If you ground something, then you can't ground the other end. In other words if you ground the - side of a 9v, then you cannot use it where + ground is needed.

Think of this supply as a battery substitute. each section creates an independent 9vDC - just like a battery. Now floating like that, a pedal circuit can ground whichever side it wants - or neither side in some cases.

[jameskpolk]

Thanks!