Occasionally I want that same effect on my Van Dyke. As others have mentioned, using regular barber clippers without the clipper guard on works. We bought a top of the line Oster Hair clipper at Sally Beauty SupplyOster - Oster Fast-Feed Clipper that I also use to cut my hair. If you look on the side, there is an adjustment bar that helps control cutting length.

I've bought inexpensive (i.e. $20-30) battery operated clippers at Walmart, etc. in the past. They don't clip as close and fall apart all too soon. Oster is a salon-quality brand. When I was in private veterinary practice, it was the brand that I bought for the groomer to use at my clinic. Let me tell you, if you want to put a pair of clippers to the test, use them grooming dogs & cats all day long. Oster's plain & simple are durable! Andis brand are pretty good also. They may cost you more at the outset, but well worth the investment.