Elektor Formant Modular

hello tw
i've put some more pics of the modules i cant figure out yet. some of
them are very home made looking! i guess thats the whole point of the
formant though....
any ideas for the 'ringbr' in particular?
btw, i'm very impressed with the over all sound quality of the system
- great big oscillators, warm and powerful filters, snappy envelopes -
its fasntastic!