I used a zapper made my a company called C-tronix in the UK (google it), it's their standard version. They're really helpful and technical and know their stuff. They also have a setting on it that does a wider range of frequency and also the standard Hulda Clark setting - all on one zapper. It was about £45, from ebay actually.
I used it for 2 weeks every day for one session. To start with I felt tingling and some movement. In two weeks I wasn't eating 7 meals a day, usually 3 with a snack at bedtime (prob more pychological). Since then if I have a moment where I'm feeling shaky, I know it's lack of minerals, prob magnesium or salt sorts me out.
The other things I did were the Clark Bowel Cleanse (tumeric capsules and fennel seed) and the parasite cleanse using the separate herbs. I haven't done the COQ10 Tapeworm thing just because the time hasn't been right.
After zapping I take a lot of magnesium and lemon water as it can sometimes make you more acidic. I've just started zapping more regualarly (but not every day) this is because I feel I am still picking them up from friends, family and my cat. All of which are resistant to the idea of zapping or killing - denial!
Good luck in whatever you decide. Hulda Clark 's book is very good - Cure to all diseases - don't get scared when you read it. The easy protocols and zapper will sort you out.