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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc.

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Old 29th Apr 2019, 9:09 am   #1
vinrads
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Default 1.5Volt supply

I have a Panasonic cassette player used to play my talking books , this uses just one 1.5volt battery , I was thinking could I utilise the 5 volt from the USB socket on the JVC DAB radio/CD player as I play the cassette through this via the jack socket, I supose the question is how to drop the 5volt to 1.5volt?

Mick.
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Old 29th Apr 2019, 9:47 am   #2
FIXITNOW
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Default Re: 1.5Volt supply

LM317. Can get a kit from ebay cheap I use them for battery valve portables to do the heater current.
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Old 29th Apr 2019, 9:48 am   #3
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Default Re: 1.5Volt supply

Assuming that the current draw is within reason, I would have thought an LM317 would do, as it can be adjusted down to 1.2V. Not sure what the minimum input votage is for it though.
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Old 29th Apr 2019, 11:38 am   #4
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Default Re: 1.5Volt supply

I have one of those modules from an eBay merchant in China. I've just tested it and will give 1.5V off a 5V supply, claimed current rating is 1.5A but I tested it with no load on a meter.
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Old 29th Apr 2019, 12:10 pm   #5
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Default Re: 1.5Volt supply

Presumably the current draw issue is as relevant to the USB source capability as the LM317? Without a heatsink, a TO220 317 should be OK for about 300mA for 5V in and 1.5V out.

Edit: Looking at the likely module, it should be OK for about an amp with the 3.5V I/O differential. I would think for 1.5A it would need the I/O differential kept very close to the 317 dropout value!
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Old 29th Apr 2019, 12:34 pm   #6
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Default Re: 1.5Volt supply

May be this is interesting: https://picclick.co.uk/AC-DC-Regulat...759456400.html

Specs:

Input Voltage :

AC 230V-50Hz 14W

Output Voltage :

DC 1.5/3/4.5/6.0/7.5/9.0/12. OV, 6.0VA(Max)
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Old 29th Apr 2019, 12:40 pm   #7
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Default Re: 1.5Volt supply

The 99p eBay module I have does have a heatsink. Agreed if anything like 1.5A was being drawn the available current from the USB socket would need to be borne in mind!
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Old 29th Apr 2019, 7:32 pm   #8
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Default Re: 1.5Volt supply

Just checked the lm317t min input is 4.2 v so this should be ok with 5 volts in to 1.5 volts out . The cassette player probably uses a DC to DC converter ,the battery lasts a good while ,I think I could just about squeeze the LM317 and other bits in the battery compartment . Thank's for all the suggestions . Mick.
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Old 29th Apr 2019, 10:46 pm   #9
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Default Re: 1.5Volt supply

Have you tried measuring the current drawn by the player in its various operation modes? The Philips EL3302 draws a pretty constant current of circa 100mA in play, record, fast forward and fast rewind modes, so a simple wire-wound series resistor of suitable wattage rating to drop the excess voltage was all that was needed to use it from a 12V car battery. They did sell a car kit consisting of a resistor in a ventilated metal box with some leads and a plug for which AFAIR they charged about a fiver in 1969: I made up my own.

Last edited by emeritus; 29th Apr 2019 at 10:51 pm.
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Old 30th Apr 2019, 8:56 am   #10
vinrads
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Default Re: 1.5Volt supply

I did consider that option ,but I would like to fit it inside the battery case hopefully the reg won't get hot maybe a bit warm warm , I think some experimenting is needed ,Mick.
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Old 30th Apr 2019, 9:21 am   #11
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Default Re: 1.5Volt supply

Or maybe look at the tiny adjustable DC-DC (buck) converters?
(''Mini DC-DC step down converter volt regulator'' has 4.75 to 23 volts in, 1.0 to 17 volts out, @ 3A, for example. Less than 2.)
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Old 30th Apr 2019, 9:25 am   #12
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Default Re: 1.5Volt supply

Wheeeeeeee!
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