Afshalders
Nas minhas incansáveis pesquisas na Web, descobri que caso não use o adaptador que vc me indicou (que pra mim é complicado de comprar) a pilha correta, ou a mais indicada é essa
http://www.fotodhm.com.br/produto/bateria-silver-oxide-387-s.htmlTEM TAMBÉM ESSE TEXTO DE UM SITE SOBRE BATERIAS DIVERSAS DAS MÁQUINAS ANTIGAS
E no final mostra as alternativas para a substituição da PX-400
PX-400
aka Energizer E400N, ANSI 1116M, IBC MR42
1.35V
Mercuric Oxide
1.40g 11.6Dx3.60H mm.
Discontinued
Asahi Pentax Spotmatic SP, SPII, SPIIa, etc.
1) The 1.55v silver oxide Energizer E387S is an exact fit. This is also sold as the Radio Shack 387S (RSU #11608452), but is a special RSU order. PhotoBattery.com has the S400PX as a replacement.
2) Both of the above are 1.55v silver oxide. They work with the Spotmatic which has voltage regulating bridge circuitry, but other older cameras may be more problematic.
3) CRIS H-B Adaptor and silver 377 batteries. The CRIS adaptor has a diode to take it down to the proper voltage, although the Spotmatic doesn't need the lower voltage.
4) Wein zinc-air cell have a stable voltage over their life and are thus suited to many older cameras. The disadvantage is that these only last a few months. Sources for Wein cells noted below.