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Failed to connect to MySQL: (1203) User howardkn already has more than 'max_user_connections' active connectionsPath: ...!weretis.net!feeder9.news.weretis.net!news.quux.org!eternal-september.org!feeder2.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Klaus Vestergaard Kragelund Newsgroups: sci.electronics.design Subject: Re: clamper Date: Tue, 5 Nov 2024 14:37:37 +0100 Organization: A noiseless patient Spider Lines: 17 Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Injection-Date: Tue, 05 Nov 2024 14:37:37 +0100 (CET) Injection-Info: dont-email.me; posting-host="c66750d18ec4043b45ff9225a404f6b6"; logging-data="1639356"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX18zMAiH3qvanlBv66Br+v/oZJocBGlXSo4=" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:oyvVQVJlTWVavSdd/BKStwwgNWk= Content-Language: en-US In-Reply-To: Bytes: 1775 On 05-11-2024 01:02, john larkin wrote: > I want a small cheap voltage clamper device. I'd like under 2 volts > drop at 1 mA, but minimal current at a few hundred millivolts. > > I tried two small diodes in series, but that's terrible. Better is a > logic-level mosfet with gate connected to drain. It clamps nicely at > 1.5 volts or so but conducts picoamps at a few hundred mV, over 1000:1 > better than the diodes. > > This will go between the force and sense leads of a 4-wire temperature > sensor thing so it automatically works in 2-wire or 4-wire mode. > > The alternative is to use two SSRs and let the user explicitely > declare 2-w or 4-w mode. > > TL431, or active opamp clamp