Autoformer Pot Core Design

[[email protected]]

Hi,

I am trying to build the circuit at this site:

http://www.williamson-labs.com/sdi.htm

Its an ultrasonic dog trainer. The problem I am having is the
autoformer.

I understand it is some kind of transformer w/ a 12:1 ratio but I
can't
figure out exactly what parts to buy to make one. I plan on getting
everying from digikey but could use some expert advice from this
forum.

if you are already at it, I also need someone to explain the overdrive
protection. Thanks.

 

[Jan Panteltje]

Hi,

if you are already at it, I also need someone to explain the overdrive
protection. Thanks.

Use the cannon.
Ultrasound has little effect on some dogs.
If the cannon is illegal, email the Whitehouse Iranian nukes are there.

 

[Bob Eld]

Hi,

I am trying to build the circuit at this site:

http://www.williamson-labs.com/sdi.htm

Its an ultrasonic dog trainer. The problem I am having is the
autoformer.

I understand it is some kind of transformer w/ a 12:1 ratio but I
can't
figure out exactly what parts to buy to make one. I plan on getting
everying from digikey but could use some expert advice from this
forum.

if you are already at it, I also need someone to explain the overdrive
protection. Thanks.

Without designing the transformer from the ground up, there is insufficient
information in at this site to properly wind your own. The author talks of
pot cores yet the picture of the Williamson Labs coil is not a pot core.
Secondly the single ended output FET driver puts DC in the tansformer. This
requires a gaped core design. The Williamson part is a open core providing a
large "gap", not closed like a pot core or torroid and is therefore suited
for the DC unbalance that this circuit gives. Unless you use a powdered
metal core, stay away form torroids, they do not have gaps. A pot core can
be used but must be gaped. The particular core, number of turns, and gap
length are unknown but can be calculated. Unfortunately the aritcle does not
provide sufficient information to simply wind a part. Digikey doesn't have
very many magnet parts in any case. If it were me, I'd try to find the
Williamson Labs part used in the circuit already wound and ready to go. Good
Luck.

 

[Homer J Simpson]

Without designing the transformer from the ground up, there is
insufficient
information in at this site to properly wind your own. The author talks of
pot cores yet the picture of the Williamson Labs coil is not a pot core.

I think they've used the term potcore loosely. I'd be inclined to look at
the tweeter maker's info.


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[Homer J Simpson]

Without designing the transformer from the ground up, there is
insufficient
information in at this site to properly wind your own. The author talks of
pot cores yet the picture of the Williamson Labs coil is not a pot core.

From the website:

* What type of pot core and winding? -- Actually, I used several pot cores
stacked, such that the primaries were driven in parallel and the secondaries
were connected in series--all phased correctly. This was done as a quick &
dirty way of achieving a "step up" and allow for enough power--before core
saturation. The specific pot core specs are only important relative to
optimum operating frequency: ~10 kHz to ~40 Khz, peaking at ~ 20 kHz.
However, this is not critical due to the broadband nature of ferrite
transformers. One could use alternate transformer technology: single large
ferrite torrid.

 

[[email protected]]

Thanks for the info. I've already asked the guy who designed it to
provide some more info, but no luck yet.

Any other ideas to get around this?

 

[Homer J Simpson]

Thanks for the info. I've already asked the guy who designed it to
provide some more info, but no luck yet.

Any other ideas to get around this?

I would look for the tweeter you are going to use and look at the design
specs. See if they have a suggested driver circuit. I would also look on
Amidon's site for information on a suitable transformer.


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[John Larkin]

Without designing the transformer from the ground up, there is insufficient
information in at this site to properly wind your own. The author talks of
pot cores yet the picture of the Williamson Labs coil is not a pot core.

Right. I mean wrong. It's not a pot core. It's a ferrite drum core.

John

 

[Homer J Simpson]

Right. I mean wrong. It's not a pot core. It's a ferrite drum core.

Looks like a bobbin but I'm not sure how much is ferrite.


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[Terry Given]

Looks like a bobbin but I'm not sure how much is ferrite.

bobbin core = drum core

I, too, was going to point this out.

Interesting idea though, I'd been thinking about doing just that.
Although a can of oven cleaner with the nozzle & tube from a can of
CRC-556 is cheaper and easier (sort of a highly corrosive mace), albeit
a lot less friendly.

I got the idea from the tech who installed my last burglar alarm. it
sounds like a pretty good idea for women living alone. Im sure a shot of
caustic soda in the face will be quite a deterrent to a would-be rapist.

Cheers
Terry

 

[Homer J Simpson]

Interesting idea though, I'd been thinking about doing just that. Although
a can of oven cleaner with the nozzle & tube from a can of CRC-556 is
cheaper and easier (sort of a highly corrosive mace), albeit a lot less
friendly.

I got the idea from the tech who installed my last burglar alarm. it
sounds like a pretty good idea for women living alone. Im sure a shot of
caustic soda in the face will be quite a deterrent to a would-be rapist.

Diluted ammonia is effective on man and beast.


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[Homer J Simpson]

Thanks for the info. I've already asked the guy who designed it to
provide some more info, but no luck yet.

Any other ideas to get around this?

Look at Amidon parts B-77-1111 and B-77-1011. One of those might match the
transformer used.


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