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Tom Harris
Greetings,
Got a requirement for a GSM/GPRS modem to run off alkaline cells, which is a little unusual, as they are designed to run straight from a Lithium-Polymer battery at about 3.6V. A common power specification for modems is 3.3v -4.6V at a few mA standby, 50mA active with 500us bursts every 5ms up to 1.5A(!) when transmitting.
As I said I need alkaline cells to run this from. What do people think to running the modem from 3x cells 4.5V nominal, 4.8V max with new cells on light load via a silicon diode to drop .7V to keep the volts below the maximumfor the modem. When the cells discharge a bit below 3.8V say, the diode isswitched out with a latching relay.
I don't care about wasting the power in the diode as the modem is switched on only for a few seconds every week, so the power lost is minimal.
Thanks for any ideas
TomH
Got a requirement for a GSM/GPRS modem to run off alkaline cells, which is a little unusual, as they are designed to run straight from a Lithium-Polymer battery at about 3.6V. A common power specification for modems is 3.3v -4.6V at a few mA standby, 50mA active with 500us bursts every 5ms up to 1.5A(!) when transmitting.
As I said I need alkaline cells to run this from. What do people think to running the modem from 3x cells 4.5V nominal, 4.8V max with new cells on light load via a silicon diode to drop .7V to keep the volts below the maximumfor the modem. When the cells discharge a bit below 3.8V say, the diode isswitched out with a latching relay.
I don't care about wasting the power in the diode as the modem is switched on only for a few seconds every week, so the power lost is minimal.
Thanks for any ideas
TomH