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Sender: "piclist-bounces@mit.edu" Date: Sat, 25 Jan 2020 14:54:22 -0800 Subject: Re: [EE] H-Bridge supply voltage spike only in "reverse" (not forward) Thread-Topic: [EE] H-Bridge supply voltage spike only in "reverse" (not forward) Thread-Index: AdXT0+mqy/gue+i5QNmLWBTlJE75oA== Message-ID: References: List-Help: List-Subscribe: , List-Unsubscribe: , In-Reply-To: Reply-To: Microcontroller discussion list - Public. Accept-Language: en-US X-MS-Exchange-Organization-AuthAs: Anonymous X-MS-Exchange-Organization-AuthSource: TS500.efplus4.local X-MS-Has-Attach: X-Auto-Response-Suppress: All X-MS-Exchange-Organization-SenderIdResult: Pass X-MS-Exchange-Organization-PRD: mit.edu X-MS-TNEF-Correlator: received-spf: Pass (protection.outlook.com: domain of gmail.com designates 209.85.210.44 as permitted sender) receiver=protection.outlook.com; client-ip=209.85.210.44; helo=mail-ot1-f44.google.com; dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to; bh=7De9vnvCv/nPMVmHGH+lY9We2v7GY4HhL+XgHUITqvU=; b=RKmmgy6tHOGpNTTW8904ePKjW48o4d4CLRwLvGjNYwEx/QpareJVeaHco/9uv/vug2 vgoJjTp4fSe4+RzQ1FHtXpHFxLalrNg5eLIqqqeB8pPuFgdodnc30fKSwCzIgVpVu9wP iZNXVWgrVd2WcS5odJq35xGxHUa8NKK/M+Utp+vj/kNwY2Z30Qlj7Z2m0v1fyDb60oQ6 4mE1N2kStrR0wKoBDKoj4ECyG13tBhFu9it9WJY9YNegPMITP9Ukcirj2FZKsdtG57pK dCMUWp18Jz/JscX47EvfRvWGXWxZqRtCiBQ7BEESSEuUpq0ULjJ8P6vPN3aIkuSREoXT OAUA== authentication-results: spf=pass (sender IP is 209.85.210.44) smtp.mailfrom=gmail.com; mit.edu; dkim=pass (signature was verified) header.d=gmail.com;mit.edu; dmarc=pass action=none header.from=gmail.com;compauth=pass reason=100 errors-to: piclist-bounces@mit.edu list-id: "Microcontroller discussion list - Public." list-post: x-beenthere: piclist@mit.edu x-mailman-version: 2.1.6 x-received: by 2002:a05:6830:1608:: with SMTP id g8mr7327664otr.169.1579992898405; Sat, 25 Jan 2020 14:54:58 -0800 (PST) x-topics: [EE] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Isolated differential probe for Vunregulated and "directly connected" for PWM pulses out of H-Bridge. Power supply is isolated from earth ground. I suppose I should try just the differential probe. On Sat, Jan 25, 2020 at 5:22 PM Sean Breheny wrote: > > How are you measuring the voltage across the H-bridge? Are you using a > differential probe? If not, where is the probe GND connected? -Jason White --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .