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Finally low pass filtering on channel 2A

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* Changed resistor to bill of material value
This commit is contained in:
Couriersud 2009-02-28 00:13:19 +00:00
parent 6a455c5dbd
commit 5a77081209
1 changed files with 15 additions and 2 deletions
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17
src/mame/drivers/btime.c
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@ -1341,8 +1341,12 @@ static const discrete_mixer_desc btime_sound_mixer_desc =
0, /* Modelled separately */ 0, /* Modelled separately */
0, 1}; 0, 1};
/* R49 has 4.7k in schematics, but listed as 47k in bill of material
* 47k gives proper low pass filtering
*/
static const discrete_op_amp_filt_info btime_opamp_desc = static const discrete_op_amp_filt_info btime_opamp_desc =
{RES_K(1), 0, RES_K(10), 0, RES_K(4.7), CAP_U(0.068), CAP_U(0.068), 0, 0, 5.0, -5.0}; {RES_K(1), 0, RES_K(10), 0, RES_K(47), CAP_U(0.068), CAP_U(0.068), 0, 0, 5.0, -5.0};
static DISCRETE_SOUND_START( btime_sound ) static DISCRETE_SOUND_START( btime_sound )
@ -1364,7 +1368,16 @@ static DISCRETE_SOUND_START( btime_sound )
DISCRETE_MIXER2(NODE_40, 1, NODE_22, NODE_30, &btime_sound_mixer_desc) DISCRETE_MIXER2(NODE_40, 1, NODE_22, NODE_30, &btime_sound_mixer_desc)
DISCRETE_CRFILTER(NODE_41, 1, NODE_40, RES_K(10), CAP_U(10)) DISCRETE_CRFILTER(NODE_41, 1, NODE_40, RES_K(10), CAP_U(10))
/* Amplifier not modelled */ /* Amplifier is upc1181H3
*
* http://www.mydarc.de/dj7oh/fad/ics/upc1181/upc1181.htm
*
* A linear frequency response is mentioned as well as a lower
* edge frequency determined by cap on pin3, however no formula given.
*
* not modelled here
*/
/* Assuming a 4 Ohm impedance speaker */ /* Assuming a 4 Ohm impedance speaker */
DISCRETE_CRFILTER(NODE_42, 1, NODE_41, 3.0, CAP_U(100)) DISCRETE_CRFILTER(NODE_42, 1, NODE_41, 3.0, CAP_U(100))