I have a 220 volt outlet over my workbench and I would like to use it. It is large, like the one for a clothes dryer. I have a 110 volt welder needing 20 amps. I know there is an adapter out there for RVs that may be 110 volts and 15amps from the 220 volts supplied at campsites. My welder blows the breakers on the 15 amp 110 circuit which is also over my workbench. Who makes one of these adapters at 20 amps and where can I find one. Thanks. Cz

What EXACTLY is this "220volt outlet"??

Not all "220" volt receptacles are the same, there are MANY different ones.
The ones in camp sites are typically 120/240v-50A. These are the same as a newer household electric range receptacle. I seriously doubt this is what you have in a garage.

What you have in a garage is likely a straight 240v-50a like for a stick welder. There are NO adapters for receptacles like this.

Tell us specifically what you welder requires. Then you should be able to rewire the circuit to fit your needs.

Chuck,
Stan is correct, you cannot simply plug in an adapter into this outlet, you will need to physically convert it. Here's how...
The first think you will need to do is to locate the circuit breaker that controls your 220V outlet and turn it off. This will be a two pole breaker, remove the wires from this breaker. If you have a spare single pole breaker, install it, and connect the black wire to it.
At this point I will need to explain about wire size, and how it relates to allowable amperage.
A # 14 wire needs a 15 amp breaker
A # 12 wire needs a 20 amp breaker
A # 10 wire needs a 30 amp breaker, and so on, this is revered to as over current protection, and you must always choose the proper breaker for your wire size.
With that being said you will need to install the correct size single pole breaker for your welder, that is as long as the wire that you have is large enough to handle your welder.
If all this checks out and you have installed the correct size breaker, you can connect your black wire to the breaker screw, and your white wire to the neutral bar. If you had a red wire connected to your two pole breaker, you can simply cap it off, and leave it in the back of your panel.
With that done, and your breaker still off you can change out the large dryer outlet, and replace it with the proper size duplex outlet, again remember to use the correct size outlet based on your over current protection
If you have any questions about specific details just ask here, and one of us will be glad to help.
If you don't feel comfortable doing the above, you can hire a licensed electrician, and they can preform this conversion for you. It is a quick job, and you can expect to pay between $100 and $200, for parts and labor.
Let me know how you make out or if you have any additional questions.